/* * Performance counter core code * * Copyright (C) 2008 Thomas Gleixner * Copyright (C) 2008-2009 Red Hat, Inc., Ingo Molnar * Copyright (C) 2008-2009 Red Hat, Inc., Peter Zijlstra * Copyright © 2009 Paul Mackerras, IBM Corp. * * For licensing details see kernel-base/COPYING */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Each CPU has a list of per CPU counters: */ DEFINE_PER_CPU(struct perf_cpu_context, perf_cpu_context); int perf_max_counters __read_mostly = 1; static int perf_reserved_percpu __read_mostly; static int perf_overcommit __read_mostly = 1; static atomic_t nr_counters __read_mostly; static atomic_t nr_mmap_counters __read_mostly; static atomic_t nr_comm_counters __read_mostly; /* * perf counter paranoia level: * 0 - not paranoid * 1 - disallow cpu counters to unpriv * 2 - disallow kernel profiling to unpriv */ int sysctl_perf_counter_paranoid __read_mostly; static inline bool perf_paranoid_cpu(void) { return sysctl_perf_counter_paranoid > 0; } static inline bool perf_paranoid_kernel(void) { return sysctl_perf_counter_paranoid > 1; } int sysctl_perf_counter_mlock __read_mostly = 512; /* 'free' kb per user */ /* * max perf counter sample rate */ int sysctl_perf_counter_sample_rate __read_mostly = 100000; static atomic64_t perf_counter_id; /* * Lock for (sysadmin-configurable) counter reservations: */ static DEFINE_SPINLOCK(perf_resource_lock); /* * Architecture provided APIs - weak aliases: */ extern __weak const struct pmu *hw_perf_counter_init(struct perf_counter *counter) { return NULL; } void __weak hw_perf_disable(void) { barrier(); } void __weak hw_perf_enable(void) { barrier(); } void __weak hw_perf_counter_setup(int cpu) { barrier(); } int __weak hw_perf_group_sched_in(struct perf_counter *group_leader, struct perf_cpu_context *cpuctx, struct perf_counter_context *ctx, int cpu) { return 0; } void __weak perf_counter_print_debug(void) { } static DEFINE_PER_CPU(int, disable_count); void __perf_disable(void) { __get_cpu_var(disable_count)++; } bool __perf_enable(void) { return !--__get_cpu_var(disable_count); } void perf_disable(void) { __perf_disable(); hw_perf_disable(); } void perf_enable(void) { if (__perf_enable()) hw_perf_enable(); } static void get_ctx(struct perf_counter_context *ctx) { WARN_ON(!atomic_inc_not_zero(&ctx->refcount)); } static void free_ctx(struct rcu_head *head) { struct perf_counter_context *ctx; ctx = container_of(head, struct perf_counter_context, rcu_head); kfree(ctx); } static void put_ctx(struct perf_counter_context *ctx) { if (atomic_dec_and_test(&ctx->refcount)) { if (ctx->parent_ctx) put_ctx(ctx->parent_ctx); if (ctx->task) put_task_struct(ctx->task); call_rcu(&ctx->rcu_head, free_ctx); } } /* * Get the perf_counter_context for a task and lock it. * This has to cope with with the fact that until it is locked, * the context could get moved to another task. */ static struct perf_counter_context * perf_lock_task_context(struct task_struct *task, unsigned long *flags) { struct perf_counter_context *ctx; rcu_read_lock(); retry: ctx = rcu_dereference(task->perf_counter_ctxp); if (ctx) { /* * If this context is a clone of another, it might * get swapped for another underneath us by * perf_counter_task_sched_out, though the * rcu_read_lock() protects us from any context * getting freed. Lock the context and check if it * got swapped before we could get the lock, and retry * if so. If we locked the right context, then it * can't get swapped on us any more. */ spin_lock_irqsave(&ctx->lock, *flags); if (ctx != rcu_dereference(task->perf_counter_ctxp)) { spin_unlock_irqrestore(&ctx->lock, *flags); goto retry; } if (!atomic_inc_not_zero(&ctx->refcount)) { spin_unlock_irqrestore(&ctx->lock, *flags); ctx = NULL; } } rcu_read_unlock(); return ctx; } /* * Get the context for a task and increment its pin_count so it * can't get swapped to another task. This also increments its * reference count so that the context can't get freed. */ static struct perf_counter_context *perf_pin_task_context(struct task_struct *task) { struct perf_counter_context *ctx; unsigned long flags; ctx = perf_lock_task_context(task, &flags); if (ctx) { ++ctx->pin_count; spin_unlock_irqrestore(&ctx->lock, flags); } return ctx; } static void perf_unpin_context(struct perf_counter_context *ctx) { unsigned long flags; spin_lock_irqsave(&ctx->lock, flags); --ctx->pin_count; spin_unlock_irqrestore(&ctx->lock, flags); put_ctx(ctx); } /* * Add a counter from the lists for its context. * Must be called with ctx->mutex and ctx->lock held. */ static void list_add_counter(struct perf_counter *counter, struct perf_counter_context *ctx) { struct perf_counter *group_leader = counter->group_leader; /* * Depending on whether it is a standalone or sibling counter, * add it straight to the context's counter list, or to the group * leader's sibling list: */ if (group_leader == counter) list_add_tail(&counter->list_entry, &ctx->counter_list); else { list_add_tail(&counter->list_entry, &group_leader->sibling_list); group_leader->nr_siblings++; } list_add_rcu(&counter->event_entry, &ctx->event_list); ctx->nr_counters++; } /* * Remove a counter from the lists for its context. * Must be called with ctx->mutex and ctx->lock held. */ static void list_del_counter(struct perf_counter *counter, struct perf_counter_context *ctx) { struct perf_counter *sibling, *tmp; if (list_empty(&counter->list_entry)) return; ctx->nr_counters--; list_del_init(&counter->list_entry); list_del_rcu(&counter->event_entry); if (counter->group_leader != counter) counter->group_leader->nr_siblings--; /* * If this was a group counter with sibling counters then * upgrade the siblings to singleton counters by adding them * to the context list directly: */ list_for_each_entry_safe(sibling, tmp, &counter->sibling_list, list_entry) { list_move_tail(&sibling->list_entry, &ctx->counter_list); sibling->group_leader = sibling; } } static void counter_sched_out(struct perf_counter *counter, struct perf_cpu_context *cpuctx, struct perf_counter_context *ctx) { if (counter->state != PERF_COUNTER_STATE_ACTIVE) return; counter->state = PERF_COUNTER_STATE_INACTIVE; counter->tstamp_stopped = ctx->time; counter->pmu->disable(counter); counter->oncpu = -1; if (!is_software_counter(counter)) cpuctx->active_oncpu--; ctx->nr_active--; if (counter->attr.exclusive || !cpuctx->active_oncpu) cpuctx->exclusive = 0; } static void group_sched_out(struct perf_counter *group_counter, struct perf_cpu_context *cpuctx, struct perf_counter_context *ctx) { struct perf_counter *counter; if (group_counter->state != PERF_COUNTER_STATE_ACTIVE) return; counter_sched_out(group_counter, cpuctx, ctx); /* * Schedule out siblings (if any): */ list_for_each_entry(counter, &group_counter->sibling_list, list_entry) counter_sched_out(counter, cpuctx, ctx); if (group_counter->attr.exclusive) cpuctx->exclusive = 0; } /* * Cross CPU call to remove a performance counter * * We disable the counter on the hardware level first. After that we * remove it from the context list. */ static void __perf_counter_remove_from_context(void *info) { struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context); struct perf_counter *counter = info; struct perf_counter_context *ctx = counter->ctx; /* * If this is a task context, we need to check whether it is * the current task context of this cpu. If not it has been * scheduled out before the smp call arrived. */ if (ctx->task && cpuctx->task_ctx != ctx) return; spin_lock(&ctx->lock); /* * Protect the list operation against NMI by disabling the * counters on a global level. */ perf_disable(); counter_sched_out(counter, cpuctx, ctx); list_del_counter(counter, ctx); if (!ctx->task) { /* * Allow more per task counters with respect to the * reservation: */ cpuctx->max_pertask = min(perf_max_counters - ctx->nr_counters, perf_max_counters - perf_reserved_percpu); } perf_enable(); spin_unlock(&ctx->lock); } /* * Remove the counter from a task's (or a CPU's) list of counters. * * Must be called with ctx->mutex held. * * CPU counters are removed with a smp call. For task counters we only * call when the task is on a CPU. * * If counter->ctx is a cloned context, callers must make sure that * every task struct that counter->ctx->task could possibly point to * remains valid. This is OK when called from perf_release since * that only calls us on the top-level context, which can't be a clone. * When called from perf_counter_exit_task, it's OK because the * context has been detached from its task. */ static void perf_counter_remove_from_context(struct perf_counter *counter) { struct perf_counter_context *ctx = counter->ctx; struct task_struct *task = ctx->task; if (!task) { /* * Per cpu counters are removed via an smp call and * the removal is always sucessful. */ smp_call_function_single(counter->cpu, __perf_counter_remove_from_context, counter, 1); return; } retry: task_oncpu_function_call(task, __perf_counter_remove_from_context, counter); spin_lock_irq(&ctx->lock); /* * If the context is active we need to retry the smp call. */ if (ctx->nr_active && !list_empty(&counter->list_entry)) { spin_unlock_irq(&ctx->lock); goto retry; } /* * The lock prevents that this context is scheduled in so we * can remove the counter safely, if the call above did not * succeed. */ if (!list_empty(&counter->list_entry)) { list_del_counter(counter, ctx); } spin_unlock_irq(&ctx->lock); } static inline u64 perf_clock(void) { return cpu_clock(smp_processor_id()); } /* * Update the record of the current time in a context. */ static void update_context_time(struct perf_counter_context *ctx) { u64 now = perf_clock(); ctx->time += now - ctx->timestamp; ctx->timestamp = now; } /* * Update the total_time_enabled and total_time_running fields for a counter. */ static void update_counter_times(struct perf_counter *counter) { struct perf_counter_context *ctx = counter->ctx; u64 run_end; if (counter->state < PERF_COUNTER_STATE_INACTIVE) return; counter->total_time_enabled = ctx->time - counter->tstamp_enabled; if (counter->state == PERF_COUNTER_STATE_INACTIVE) run_end = counter->tstamp_stopped; else run_end = ctx->time; counter->total_time_running = run_end - counter->tstamp_running; } /* * Update total_time_enabled and total_time_running for all counters in a group. */ static void update_group_times(struct perf_counter *leader) { struct perf_counter *counter; update_counter_times(leader); list_for_each_entry(counter, &leader->sibling_list, list_entry) update_counter_times(counter); } /* * Cross CPU call to disable a performance counter */ static void __perf_counter_disable(void *info) { struct perf_counter *counter = info; struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context); struct perf_counter_context *ctx = counter->ctx; /* * If this is a per-task counter, need to check whether this * counter's task is the current task on this cpu. */ if (ctx->task && cpuctx->task_ctx != ctx) return; spin_lock(&ctx->lock); /* * If the counter is on, turn it off. * If it is in error state, leave it in error state. */ if (counter->state >= PERF_COUNTER_STATE_INACTIVE) { update_context_time(ctx); update_counter_times(counter); if (counter == counter->group_leader) group_sched_out(counter, cpuctx, ctx); else counter_sched_out(counter, cpuctx, ctx); counter->state = PERF_COUNTER_STATE_OFF; } spin_unlock(&ctx->lock); } /* * Disable a counter. * * If counter->ctx is a cloned context, callers must make sure that * every task struct that counter->ctx->task could possibly point to * remains valid. This condition is satisifed when called through * perf_counter_for_each_child or perf_counter_for_each because they * hold the top-level counter's child_mutex, so any descendant that * goes to exit will block in sync_child_counter. * When called from perf_pending_counter it's OK because counter->ctx * is the current context on this CPU and preemption is disabled, * hence we can't get into perf_counter_task_sched_out for this context. */ static void perf_counter_disable(struct perf_counter *counter) { struct perf_counter_context *ctx = counter->ctx; struct task_struct *task = ctx->task; if (!task) { /* * Disable the counter on the cpu that it's on */ smp_call_function_single(counter->cpu, __perf_counter_disable, counter, 1); return; } retry: task_oncpu_function_call(task, __perf_counter_disable, counter); spin_lock_irq(&ctx->lock); /* * If the counter is still active, we need to retry the cross-call. */ if (counter->state == PERF_COUNTER_STATE_ACTIVE) { spin_unlock_irq(&ctx->lock); goto retry; } /* * Since we have the lock this context can't be scheduled * in, so we can change the state safely. */ if (counter->state == PERF_COUNTER_STATE_INACTIVE) { update_counter_times(counter); counter->state = PERF_COUNTER_STATE_OFF; } spin_unlock_irq(&ctx->lock); } static int counter_sched_in(struct perf_counter *counter, struct perf_cpu_context *cpuctx, struct perf_counter_context *ctx, int cpu) { if (counter->state <= PERF_COUNTER_STATE_OFF) return 0; counter->state = PERF_COUNTER_STATE_ACTIVE; counter->oncpu = cpu; /* TODO: put 'cpu' into cpuctx->cpu */ /* * The new state must be visible before we turn it on in the hardware: */ smp_wmb(); if (counter->pmu->enable(counter)) { counter->state = PERF_COUNTER_STATE_INACTIVE; counter->oncpu = -1; return -EAGAIN; } counter->tstamp_running += ctx->time - counter->tstamp_stopped; if (!is_software_counter(counter)) cpuctx->active_oncpu++; ctx->nr_active++; if (counter->attr.exclusive) cpuctx->exclusive = 1; return 0; } static int group_sched_in(struct perf_counter *group_counter, struct perf_cpu_context *cpuctx, struct perf_counter_context *ctx, int cpu) { struct perf_counter *counter, *partial_group; int ret; if (group_counter->state == PERF_COUNTER_STATE_OFF) return 0; ret = hw_perf_group_sched_in(group_counter, cpuctx, ctx, cpu); if (ret) return ret < 0 ? ret : 0; if (counter_sched_in(group_counter, cpuctx, ctx, cpu)) return -EAGAIN; /* * Schedule in siblings as one group (if any): */ list_for_each_entry(counter, &group_counter->sibling_list, list_entry) { if (counter_sched_in(counter, cpuctx, ctx, cpu)) { partial_group = counter; goto group_error; } } return 0; group_error: /* * Groups can be scheduled in as one unit only, so undo any * partial group before returning: */ list_for_each_entry(counter, &group_counter->sibling_list, list_entry) { if (counter == partial_group) break; counter_sched_out(counter, cpuctx, ctx); } counter_sched_out(group_counter, cpuctx, ctx); return -EAGAIN; } /* * Return 1 for a group consisting entirely of software counters, * 0 if the group contains any hardware counters. */ static int is_software_only_group(struct perf_counter *leader) { struct perf_counter *counter; if (!is_software_counter(leader)) return 0; list_for_each_entry(counter, &leader->sibling_list, list_entry) if (!is_software_counter(counter)) return 0; return 1; } /* * Work out whether we can put this counter group on the CPU now. */ static int group_can_go_on(struct perf_counter *counter, struct perf_cpu_context *cpuctx, int can_add_hw) { /* * Groups consisting entirely of software counters can always go on. */ if (is_software_only_group(counter)) return 1; /* * If an exclusive group is already on, no other hardware * counters can go on. */ if (cpuctx->exclusive) return 0; /* * If this group is exclusive and there are already * counters on the CPU, it can't go on. */ if (counter->attr.exclusive && cpuctx->active_oncpu) return 0; /* * Otherwise, try to add it if all previous groups were able * to go on. */ return can_add_hw; } static void add_counter_to_ctx(struct perf_counter *counter, struct perf_counter_context *ctx) { list_add_counter(counter, ctx); counter->tstamp_enabled = ctx->time; counter->tstamp_running = ctx->time; counter->tstamp_stopped = ctx->time; } /* * Cross CPU call to install and enable a performance counter * * Must be called with ctx->mutex held */ static void __perf_install_in_context(void *info) { struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context); struct perf_counter *counter = info; struct perf_counter_context *ctx = counter->ctx; struct perf_counter *leader = counter->group_leader; int cpu = smp_processor_id(); int err; /* * If this is a task context, we need to check whether it is * the current task context of this cpu. If not it has been * scheduled out before the smp call arrived. * Or possibly this is the right context but it isn't * on this cpu because it had no counters. */ if (ctx->task && cpuctx->task_ctx != ctx) { if (cpuctx->task_ctx || ctx->task != current) return; cpuctx->task_ctx = ctx; } spin_lock(&ctx->lock); ctx->is_active = 1; update_context_time(ctx); /* * Protect the list operation against NMI by disabling the * counters on a global level. NOP for non NMI based counters. */ perf_disable(); add_counter_to_ctx(counter, ctx); /* * Don't put the counter on if it is disabled or if * it is in a group and the group isn't on. */ if (counter->state != PERF_COUNTER_STATE_INACTIVE || (leader != counter && leader->state != PERF_COUNTER_STATE_ACTIVE)) goto unlock; /* * An exclusive counter can't go on if there are already active * hardware counters, and no hardware counter can go on if there * is already an exclusive counter on. */ if (!group_can_go_on(counter, cpuctx, 1)) err = -EEXIST; else err = counter_sched_in(counter, cpuctx, ctx, cpu); if (err) { /* * This counter couldn't go on. If it is in a group * then we have to pull the whole group off. * If the counter group is pinned then put it in error state. */ if (leader != counter) group_sched_out(leader, cpuctx, ctx); if (leader->attr.pinned) { update_group_times(leader); leader->state = PERF_COUNTER_STATE_ERROR; } } if (!err && !ctx->task && cpuctx->max_pertask) cpuctx->max_pertask--; unlock: perf_enable(); spin_unlock(&ctx->lock); } /* * Attach a performance counter to a context * * First we add the counter to the list with the hardware enable bit * in counter->hw_config cleared. * * If the counter is attached to a task which is on a CPU we use a smp * call to enable it in the task context. The task might have been * scheduled away, but we check this in the smp call again. * * Must be called with ctx->mutex held. */ static void perf_install_in_context(struct perf_counter_context *ctx, struct perf_counter *counter, int cpu) { struct task_struct *task = ctx->task; if (!task) { /* * Per cpu counters are installed via an smp call and * the install is always sucessful. */ smp_call_function_single(cpu, __perf_install_in_context, counter, 1); return; } retry: task_oncpu_function_call(task, __perf_install_in_context, counter); spin_lock_irq(&ctx->lock); /* * we need to retry the smp call. */ if (ctx->is_active && list_empty(&counter->list_entry)) { spin_unlock_irq(&ctx->lock); goto retry; } /* * The lock prevents that this context is scheduled in so we * can add the counter safely, if it the call above did not * succeed. */ if (list_empty(&counter->list_entry)) add_counter_to_ctx(counter, ctx); spin_unlock_irq(&ctx->lock); } /* * Cross CPU call to enable a performance counter */ static void __perf_counter_enable(void *info) { struct perf_counter *counter = info; struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context); struct perf_counter_context *ctx = counter->ctx; struct perf_counter *leader = counter->group_leader; int err; /* * If this is a per-task counter, need to check whether this * counter's task is the current task on this cpu. */ if (ctx->task && cpuctx->task_ctx != ctx) { if (cpuctx->task_ctx || ctx->task != current) return; cpuctx->task_ctx = ctx; } spin_lock(&ctx->lock); ctx->is_active = 1; update_context_time(ctx); if (counter->state >= PERF_COUNTER_STATE_INACTIVE) goto unlock; counter->state = PERF_COUNTER_STATE_INACTIVE; counter->tstamp_enabled = ctx->time - counter->total_time_enabled; /* * If the counter is in a group and isn't the group leader, * then don't put it on unless the group is on. */ if (leader != counter && leader->state != PERF_COUNTER_STATE_ACTIVE) goto unlock; if (!group_can_go_on(counter, cpuctx, 1)) { err = -EEXIST; } else { perf_disable(); if (counter == leader) err = group_sched_in(counter, cpuctx, ctx, smp_processor_id()); else err = counter_sched_in(counter, cpuctx, ctx, smp_processor_id()); perf_enable(); } if (err) { /* * If this counter can't go on and it's part of a * group, then the whole group has to come off. */ if (leader != counter) group_sched_out(leader, cpuctx, ctx); if (leader->attr.pinned) { update_group_times(leader); leader->state = PERF_COUNTER_STATE_ERROR; } } unlock: spin_unlock(&ctx->lock); } /* * Enable a counter. * * If counter->ctx is a cloned context, callers must make sure that * every task struct that counter->ctx->task could possibly point to * remains valid. This condition is satisfied when called through * perf_counter_for_each_child or perf_counter_for_each as described * for perf_counter_disable. */ static void perf_counter_enable(struct perf_counter *counter) { struct perf_counter_context *ctx = counter->ctx; struct task_struct *task = ctx->task; if (!task) { /* * Enable the counter on the cpu that it's on */ smp_call_function_single(counter->cpu, __perf_counter_enable, counter, 1); return; } spin_lock_irq(&ctx->lock); if (counter->state >= PERF_COUNTER_STATE_INACTIVE) goto out; /* * If the counter is in error state, clear that first. * That way, if we see the counter in error state below, we * know that it has gone back into error state, as distinct * from the task having been scheduled away before the * cross-call arrived. */ if (counter->state == PERF_COUNTER_STATE_ERROR) counter->state = PERF_COUNTER_STATE_OFF; retry: spin_unlock_irq(&ctx->lock); task_oncpu_function_call(task, __perf_counter_enable, counter); spin_lock_irq(&ctx->lock); /* * If the context is active and the counter is still off, * we need to retry the cross-call. */ if (ctx->is_active && counter->state == PERF_COUNTER_STATE_OFF) goto retry; /* * Since we have the lock this context can't be scheduled * in, so we can change the state safely. */ if (counter->state == PERF_COUNTER_STATE_OFF) { counter->state = PERF_COUNTER_STATE_INACTIVE; counter->tstamp_enabled = ctx->time - counter->total_time_enabled; } out: spin_unlock_irq(&ctx->lock); } static int perf_counter_refresh(struct perf_counter *counter, int refresh) { /* * not supported on inherited counters */ if (counter->attr.inherit) return -EINVAL; atomic_add(refresh, &counter->event_limit); perf_counter_enable(counter); return 0; } void __perf_counter_sched_out(struct perf_counter_context *ctx, struct perf_cpu_context *cpuctx) { struct perf_counter *counter; spin_lock(&ctx->lock); ctx->is_active = 0; if (likely(!ctx->nr_counters)) goto out; update_context_time(ctx); perf_disable(); if (ctx->nr_active) { list_for_each_entry(counter, &ctx->counter_list, list_entry) { if (counter != counter->group_leader) counter_sched_out(counter, cpuctx, ctx); else group_sched_out(counter, cpuctx, ctx); } } perf_enable(); out: spin_unlock(&ctx->lock); } /* * Test whether two contexts are equivalent, i.e. whether they * have both been cloned from the same version of the same context * and they both have the same number of enabled counters. * If the number of enabled counters is the same, then the set * of enabled counters should be the same, because these are both * inherited contexts, therefore we can't access individual counters * in them directly with an fd; we can only enable/disable all * counters via prctl, or enable/disable all counters in a family * via ioctl, which will have the same effect on both contexts. */ static int context_equiv(struct perf_counter_context *ctx1, struct perf_counter_context *ctx2) { return ctx1->parent_ctx && ctx1->parent_ctx == ctx2->parent_ctx && ctx1->parent_gen == ctx2->parent_gen && !ctx1->pin_count && !ctx2->pin_count; } /* * Called from scheduler to remove the counters of the current task, * with interrupts disabled. * * We stop each counter and update the counter value in counter->count. * * This does not protect us against NMI, but disable() * sets the disabled bit in the control field of counter _before_ * accessing the counter control register. If a NMI hits, then it will * not restart the counter. */ void perf_counter_task_sched_out(struct task_struct *task, struct task_struct *next, int cpu) { struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu); struct perf_counter_context *ctx = task->perf_counter_ctxp; struct perf_counter_context *next_ctx; struct perf_counter_context *parent; struct pt_regs *regs; int do_switch = 1; regs = task_pt_regs(task); perf_swcounter_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 1, regs, 0); if (likely(!ctx || !cpuctx->task_ctx)) return; update_context_time(ctx); rcu_read_lock(); parent = rcu_dereference(ctx->parent_ctx); next_ctx = next->perf_counter_ctxp; if (parent && next_ctx && rcu_dereference(next_ctx->parent_ctx) == parent) { /* * Looks like the two contexts are clones, so we might be * able to optimize the context switch. We lock both * contexts and check that they are clones under the * lock (including re-checking that neither has been * uncloned in the meantime). It doesn't matter which * order we take the locks because no other cpu could * be trying to lock both of these tasks. */ spin_lock(&ctx->lock); spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING); if (context_equiv(ctx, next_ctx)) { /* * XXX do we need a memory barrier of sorts * wrt to rcu_dereference() of perf_counter_ctxp */ task->perf_counter_ctxp = next_ctx; next->perf_counter_ctxp = ctx; ctx->task = next; next_ctx->task = task; do_switch = 0; } spin_unlock(&next_ctx->lock); spin_unlock(&ctx->lock); } rcu_read_unlock(); if (do_switch) { __perf_counter_sched_out(ctx, cpuctx); cpuctx->task_ctx = NULL; } } /* * Called with IRQs disabled */ static void __perf_counter_task_sched_out(struct perf_counter_context *ctx) { struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context); if (!cpuctx->task_ctx) return; if (WARN_ON_ONCE(ctx != cpuctx->task_ctx)) return; __perf_counter_sched_out(ctx, cpuctx); cpuctx->task_ctx = NULL; } /* * Called with IRQs disabled */ static void perf_counter_cpu_sched_out(struct perf_cpu_context *cpuctx) { __perf_counter_sched_out(&cpuctx->ctx, cpuctx); } static void __perf_counter_sched_in(struct perf_counter_context *ctx, struct perf_cpu_context *cpuctx, int cpu) { struct perf_counter *counter; int can_add_hw = 1; spin_lock(&ctx->lock); ctx->is_active = 1; if (likely(!ctx->nr_counters)) goto out; ctx->timestamp = perf_clock(); perf_disable(); /* * First go through the list and put on any pinned groups * in order to give them the best chance of going on. */ list_for_each_entry(counter, &ctx->counter_list, list_entry) { if (counter->state <= PERF_COUNTER_STATE_OFF || !counter->attr.pinned) continue; if (counter->cpu != -1 && counter->cpu != cpu) continue; if (counter != counter->group_leader) counter_sched_in(counter, cpuctx, ctx, cpu); else { if (group_can_go_on(counter, cpuctx, 1)) group_sched_in(counter, cpuctx, ctx, cpu); } /* * If this pinned group hasn't been scheduled, * put it in error state. */ if (counter->state == PERF_COUNTER_STATE_INACTIVE) { update_group_times(counter); counter->state = PERF_COUNTER_STATE_ERROR; } } list_for_each_entry(counter, &ctx->counter_list, list_entry) { /* * Ignore counters in OFF or ERROR state, and * ignore pinned counters since we did them already. */ if (counter->state <= PERF_COUNTER_STATE_OFF || counter->attr.pinned) continue; /* * Listen to the 'cpu' scheduling filter constraint * of counters: */ if (counter->cpu != -1 && counter->cpu != cpu) continue; if (counter != counter->group_leader) { if (counter_sched_in(counter, cpuctx, ctx, cpu)) can_add_hw = 0; } else { if (group_can_go_on(counter, cpuctx, can_add_hw)) { if (group_sched_in(counter, cpuctx, ctx, cpu)) can_add_hw = 0; } } } perf_enable(); out: spin_unlock(&ctx->lock); } /* * Called from scheduler to add the counters of the current task * with interrupts disabled. * * We restore the counter value and then enable it. * * This does not protect us against NMI, but enable() * sets the enabled bit in the control field of counter _before_ * accessing the counter control register. If a NMI hits, then it will * keep the counter running. */ void perf_counter_task_sched_in(struct task_struct *task, int cpu) { struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu); struct perf_counter_context *ctx = task->perf_counter_ctxp; if (likely(!ctx)) return; if (cpuctx->task_ctx == ctx) return; __perf_counter_sched_in(ctx, cpuctx, cpu); cpuctx->task_ctx = ctx; } static void perf_counter_cpu_sched_in(struct perf_cpu_context *cpuctx, int cpu) { struct perf_counter_context *ctx = &cpuctx->ctx; __perf_counter_sched_in(ctx, cpuctx, cpu); } #define MAX_INTERRUPTS (~0ULL) static void perf_log_throttle(struct perf_counter *counter, int enable); static void perf_log_period(struct perf_counter *counter, u64 period); static void perf_adjust_period(struct perf_counter *counter, u64 events) { struct hw_perf_counter *hwc = &counter->hw; u64 period, sample_period; s64 delta; events *= hwc->sample_period; period = div64_u64(events, counter->attr.sample_freq); delta = (s64)(period - hwc->sample_period); delta = (delta + 7) / 8; /* low pass filter */ sample_period = hwc->sample_period + delta; if (!sample_period) sample_period = 1; perf_log_period(counter, sample_period); hwc->sample_period = sample_period; } static void perf_ctx_adjust_freq(struct perf_counter_context *ctx) { struct perf_counter *counter; struct hw_perf_counter *hwc; u64 interrupts, freq; spin_lock(&ctx->lock); list_for_each_entry(counter, &ctx->counter_list, list_entry) { if (counter->state != PERF_COUNTER_STATE_ACTIVE) continue; hwc = &counter->hw; interrupts = hwc->interrupts; hwc->interrupts = 0; /* * unthrottle counters on the tick */ if (interrupts == MAX_INTERRUPTS) { perf_log_throttle(counter, 1); counter->pmu->unthrottle(counter); interrupts = 2*sysctl_perf_counter_sample_rate/HZ; } if (!counter->attr.freq || !counter->attr.sample_freq) continue; /* * if the specified freq < HZ then we need to skip ticks */ if (counter->attr.sample_freq < HZ) { freq = counter->attr.sample_freq; hwc->freq_count += freq; hwc->freq_interrupts += interrupts; if (hwc->freq_count < HZ) continue; interrupts = hwc->freq_interrupts; hwc->freq_interrupts = 0; hwc->freq_count -= HZ; } else freq = HZ; perf_adjust_period(counter, freq * interrupts); /* * In order to avoid being stalled by an (accidental) huge * sample period, force reset the sample period if we didn't * get any events in this freq period. */ if (!interrupts) { perf_disable(); counter->pmu->disable(counter); atomic64_set(&hwc->period_left, 0); counter->pmu->enable(counter); perf_enable(); } } spin_unlock(&ctx->lock); } /* * Round-robin a context's counters: */ static void rotate_ctx(struct perf_counter_context *ctx) { struct perf_counter *counter; if (!ctx->nr_counters) return; spin_lock(&ctx->lock); /* * Rotate the first entry last (works just fine for group counters too): */ perf_disable(); list_for_each_entry(counter, &ctx->counter_list, list_entry) { list_move_tail(&counter->list_entry, &ctx->counter_list); break; } perf_enable(); spin_unlock(&ctx->lock); } void perf_counter_task_tick(struct task_struct *curr, int cpu) { struct perf_cpu_context *cpuctx; struct perf_counter_context *ctx; if (!atomic_read(&nr_counters)) return; cpuctx = &per_cpu(perf_cpu_context, cpu); ctx = curr->perf_counter_ctxp; perf_ctx_adjust_freq(&cpuctx->ctx); if (ctx) perf_ctx_adjust_freq(ctx); perf_counter_cpu_sched_out(cpuctx); if (ctx) __perf_counter_task_sched_out(ctx); rotate_ctx(&cpuctx->ctx); if (ctx) rotate_ctx(ctx); perf_counter_cpu_sched_in(cpuctx, cpu); if (ctx) perf_counter_task_sched_in(curr, cpu); } /* * Cross CPU call to read the hardware counter */ static void __read(void *info) { struct perf_counter *counter = info; struct perf_counter_context *ctx = counter->ctx; unsigned long flags; local_irq_save(flags); if (ctx->is_active) update_context_time(ctx); counter->pmu->read(counter); update_counter_times(counter); local_irq_restore(flags); } static u64 perf_counter_read(struct perf_counter *counter) { /* * If counter is enabled and currently active on a CPU, update the * value in the counter structure: */ if (counter->state == PERF_COUNTER_STATE_ACTIVE) { smp_call_function_single(counter->oncpu, __read, counter, 1); } else if (counter->state == PERF_COUNTER_STATE_INACTIVE) { update_counter_times(counter); } return atomic64_read(&counter->count); } /* * Initialize the perf_counter context in a task_struct: */ static void __perf_counter_init_context(struct perf_counter_context *ctx, struct task_struct *task) { memset(ctx, 0, sizeof(*ctx)); spin_lock_init(&ctx->lock); mutex_init(&ctx->mutex); INIT_LIST_HEAD(&ctx->counter_list); INIT_LIST_HEAD(&ctx->event_list); atomic_set(&ctx->refcount, 1); ctx->task = task; } static struct perf_counter_context *find_get_context(pid_t pid, int cpu) { struct perf_counter_context *parent_ctx; struct perf_counter_context *ctx; struct perf_cpu_context *cpuctx; struct task_struct *task; unsigned long flags; int err; /* * If cpu is not a wildcard then this is a percpu counter: */ if (cpu != -1) { /* Must be root to operate on a CPU counter: */ if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN)) return ERR_PTR(-EACCES); if (cpu < 0 || cpu > num_possible_cpus()) return ERR_PTR(-EINVAL); /* * We could be clever and allow to attach a counter to an * offline CPU and activate it when the CPU comes up, but * that's for later. */ if (!cpu_isset(cpu, cpu_online_map)) return ERR_PTR(-ENODEV); cpuctx = &per_cpu(perf_cpu_context, cpu); ctx = &cpuctx->ctx; get_ctx(ctx); return ctx; } rcu_read_lock(); if (!pid) task = current; else task = find_task_by_vpid(pid); if (task) get_task_struct(task); rcu_read_unlock(); if (!task) return ERR_PTR(-ESRCH); /* * Can't attach counters to a dying task. */ err = -ESRCH; if (task->flags & PF_EXITING) goto errout; /* Reuse ptrace permission checks for now. */ err = -EACCES; if (!ptrace_may_access(task, PTRACE_MODE_READ)) goto errout; retry: ctx = perf_lock_task_context(task, &flags); if (ctx) { parent_ctx = ctx->parent_ctx; if (parent_ctx) { put_ctx(parent_ctx); ctx->parent_ctx = NULL; /* no longer a clone */ } spin_unlock_irqrestore(&ctx->lock, flags); } if (!ctx) { ctx = kmalloc(sizeof(struct perf_counter_context), GFP_KERNEL); err = -ENOMEM; if (!ctx) goto errout; __perf_counter_init_context(ctx, task); get_ctx(ctx); if (cmpxchg(&task->perf_counter_ctxp, NULL, ctx)) { /* * We raced with some other task; use * the context they set. */ kfree(ctx); goto retry; } get_task_struct(task); } put_task_struct(task); return ctx; errout: put_task_struct(task); return ERR_PTR(err); } static void free_counter_rcu(struct rcu_head *head) { struct perf_counter *counter; counter = container_of(head, struct perf_counter, rcu_head); if (counter->ns) put_pid_ns(counter->ns); kfree(counter); } static void perf_pending_sync(struct perf_counter *counter); static void free_counter(struct perf_counter *counter) { perf_pending_sync(counter); if (!counter->parent) { atomic_dec(&nr_counters); if (counter->attr.mmap) atomic_dec(&nr_mmap_counters); if (counter->attr.comm) atomic_dec(&nr_comm_counters); } if (counter->destroy) counter->destroy(counter); put_ctx(counter->ctx); call_rcu(&counter->rcu_head, free_counter_rcu); } /* * Called when the last reference to the file is gone. */ static int perf_release(struct inode *inode, struct file *file) { struct perf_counter *counter = file->private_data; struct perf_counter_context *ctx = counter->ctx; file->private_data = NULL; WARN_ON_ONCE(ctx->parent_ctx); mutex_lock(&ctx->mutex); perf_counter_remove_from_context(counter); mutex_unlock(&ctx->mutex); mutex_lock(&counter->owner->perf_counter_mutex); list_del_init(&counter->owner_entry); mutex_unlock(&counter->owner->perf_counter_mutex); put_task_struct(counter->owner); free_counter(counter); return 0; } /* * Read the performance counter - simple non blocking version for now */ static ssize_t perf_read_hw(struct perf_counter *counter, char __user *buf, size_t count) { u64 values[4]; int n; /* * Return end-of-file for a read on a counter that is in * error state (i.e. because it was pinned but it couldn't be * scheduled on to the CPU at some point). */ if (counter->state == PERF_COUNTER_STATE_ERROR) return 0; WARN_ON_ONCE(counter->ctx->parent_ctx); mutex_lock(&counter->child_mutex); values[0] = perf_counter_read(counter); n = 1; if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) values[n++] = counter->total_time_enabled + atomic64_read(&counter->child_total_time_enabled); if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) values[n++] = counter->total_time_running + atomic64_read(&counter->child_total_time_running); if (counter->attr.read_format & PERF_FORMAT_ID) values[n++] = counter->id; mutex_unlock(&counter->child_mutex); if (count < n * sizeof(u64)) return -EINVAL; count = n * sizeof(u64); if (copy_to_user(buf, values, count)) return -EFAULT; return count; } static ssize_t perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { struct perf_counter *counter = file->private_data; return perf_read_hw(counter, buf, count); } static unsigned int perf_poll(struct file *file, poll_table *wait) { struct perf_counter *counter = file->private_data; struct perf_mmap_data *data; unsigned int events = POLL_HUP; rcu_read_lock(); data = rcu_dereference(counter->data); if (data) events = atomic_xchg(&data->poll, 0); rcu_read_unlock(); poll_wait(file, &counter->waitq, wait); return events; } static void perf_counter_reset(struct perf_counter *counter) { (void)perf_counter_read(counter); atomic64_set(&counter->count, 0); perf_counter_update_userpage(counter); } /* * Holding the top-level counter's child_mutex means that any * descendant process that has inherited this counter will block * in sync_child_counter if it goes to exit, thus satisfying the * task existence requirements of perf_counter_enable/disable. */ static void perf_counter_for_each_child(struct perf_counter *counter, void (*func)(struct perf_counter *)) { struct perf_counter *child; WARN_ON_ONCE(counter->ctx->parent_ctx); mutex_lock(&counter->child_mutex); func(counter); list_for_each_entry(child, &counter->child_list, child_list) func(child); mutex_unlock(&counter->child_mutex); } static void perf_counter_for_each(struct perf_counter *counter, void (*func)(struct perf_counter *)) { struct perf_counter_context *ctx = counter->ctx; struct perf_counter *sibling; WARN_ON_ONCE(ctx->parent_ctx); mutex_lock(&ctx->mutex); counter = counter->group_leader; perf_counter_for_each_child(counter, func); func(counter); list_for_each_entry(sibling, &counter->sibling_list, list_entry) perf_counter_for_each_child(counter, func); mutex_unlock(&ctx->mutex); } static int perf_counter_period(struct perf_counter *counter, u64 __user *arg) { struct perf_counter_context *ctx = counter->ctx; unsigned long size; int ret = 0; u64 value; if (!counter->attr.sample_period) return -EINVAL; size = copy_from_user(&value, arg, sizeof(value)); if (size != sizeof(value)) return -EFAULT; if (!value) return -EINVAL; spin_lock_irq(&ctx->lock); if (counter->attr.freq) { if (value > sysctl_perf_counter_sample_rate) { ret = -EINVAL; goto unlock; } counter->attr.sample_freq = value; } else { perf_log_period(counter, value); counter->attr.sample_period = value; counter->hw.sample_period = value; } unlock: spin_unlock_irq(&ctx->lock); return ret; } static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct perf_counter *counter = file->private_data; void (*func)(struct perf_counter *); u32 flags = arg; switch (cmd) { case PERF_COUNTER_IOC_ENABLE: func = perf_counter_enable; break; case PERF_COUNTER_IOC_DISABLE: func = perf_counter_disable; break; case PERF_COUNTER_IOC_RESET: func = perf_counter_reset; break; case PERF_COUNTER_IOC_REFRESH: return perf_counter_refresh(counter, arg); case PERF_COUNTER_IOC_PERIOD: return perf_counter_period(counter, (u64 __user *)arg); default: return -ENOTTY; } if (flags & PERF_IOC_FLAG_GROUP) perf_counter_for_each(counter, func); else perf_counter_for_each_child(counter, func); return 0; } int perf_counter_task_enable(void) { struct perf_counter *counter; mutex_lock(¤t->perf_counter_mutex); list_for_each_entry(counter, ¤t->perf_counter_list, owner_entry) perf_counter_for_each_child(counter, perf_counter_enable); mutex_unlock(¤t->perf_counter_mutex); return 0; } int perf_counter_task_disable(void) { struct perf_counter *counter; mutex_lock(¤t->perf_counter_mutex); list_for_each_entry(counter, ¤t->perf_counter_list, owner_entry) perf_counter_for_each_child(counter, perf_counter_disable); mutex_unlock(¤t->perf_counter_mutex); return 0; } static int perf_counter_index(struct perf_counter *counter) { if (counter->state != PERF_COUNTER_STATE_ACTIVE) return 0; return counter->hw.idx + 1 - PERF_COUNTER_INDEX_OFFSET; } /* * Callers need to ensure there can be no nesting of this function, otherwise * the seqlock logic goes bad. We can not serialize this because the arch * code calls this from NMI context. */ void perf_counter_update_userpage(struct perf_counter *counter) { struct perf_counter_mmap_page *userpg; struct perf_mmap_data *data; rcu_read_lock(); data = rcu_dereference(counter->data); if (!data) goto unlock; userpg = data->user_page; /* * Disable preemption so as to not let the corresponding user-space * spin too long if we get preempted. */ preempt_disable(); ++userpg->lock; barrier(); userpg->index = perf_counter_index(counter); userpg->offset = atomic64_read(&counter->count); if (counter->state == PERF_COUNTER_STATE_ACTIVE) userpg->offset -= atomic64_read(&counter->hw.prev_count); userpg->time_enabled = counter->total_time_enabled + atomic64_read(&counter->child_total_time_enabled); userpg->time_running = counter->total_time_running + atomic64_read(&counter->child_total_time_running); barrier(); ++userpg->lock; preempt_enable(); unlock: rcu_read_unlock(); } static int perf_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) { struct perf_counter *counter = vma->vm_file->private_data; struct perf_mmap_data *data; int ret = VM_FAULT_SIGBUS; if (vmf->flags & FAULT_FLAG_MKWRITE) { if (vmf->pgoff == 0) ret = 0; return ret; } rcu_read_lock(); data = rcu_dereference(counter->data); if (!data) goto unlock; if (vmf->pgoff == 0) { vmf->page = virt_to_page(data->user_page); } else { int nr = vmf->pgoff - 1; if ((unsigned)nr > data->nr_pages) goto unlock; if (vmf->flags & FAULT_FLAG_WRITE) goto unlock; vmf->page = virt_to_page(data->data_pages[nr]); } get_page(vmf->page); vmf->page->mapping = vma->vm_file->f_mapping; vmf->page->index = vmf->pgoff; ret = 0; unlock: rcu_read_unlock(); return ret; } static int perf_mmap_data_alloc(struct perf_counter *counter, int nr_pages) { struct perf_mmap_data *data; unsigned long size; int i; WARN_ON(atomic_read(&counter->mmap_count)); size = sizeof(struct perf_mmap_data); size += nr_pages * sizeof(void *); data = kzalloc(size, GFP_KERNEL); if (!data) goto fail; data->user_page = (void *)get_zeroed_page(GFP_KERNEL); if (!data->user_page) goto fail_user_page; for (i = 0; i < nr_pages; i++) { data->data_pages[i] = (void *)get_zeroed_page(GFP_KERNEL); if (!data->data_pages[i]) goto fail_data_pages; } data->nr_pages = nr_pages; atomic_set(&data->lock, -1); rcu_assign_pointer(counter->data, data); return 0; fail_data_pages: for (i--; i >= 0; i--) free_page((unsigned long)data->data_pages[i]); free_page((unsigned long)data->user_page); fail_user_page: kfree(data); fail: return -ENOMEM; } static void perf_mmap_free_page(unsigned long addr) { struct page *page = virt_to_page(addr); page->mapping = NULL; __free_page(page); } static void __perf_mmap_data_free(struct rcu_head *rcu_head) { struct perf_mmap_data *data; int i; data = container_of(rcu_head, struct perf_mmap_data, rcu_head); perf_mmap_free_page((unsigned long)data->user_page); for (i = 0; i < data->nr_pages; i++) perf_mmap_free_page((unsigned long)data->data_pages[i]); kfree(data); } static void perf_mmap_data_free(struct perf_counter *counter) { struct perf_mmap_data *data = counter->data; WARN_ON(atomic_read(&counter->mmap_count)); rcu_assign_pointer(counter->data, NULL); call_rcu(&data->rcu_head, __perf_mmap_data_free); } static void perf_mmap_open(struct vm_area_struct *vma) { struct perf_counter *counter = vma->vm_file->private_data; atomic_inc(&counter->mmap_count); } static void perf_mmap_close(struct vm_area_struct *vma) { struct perf_counter *counter = vma->vm_file->private_data; WARN_ON_ONCE(counter->ctx->parent_ctx); if (atomic_dec_and_mutex_lock(&counter->mmap_count, &counter->mmap_mutex)) { struct user_struct *user = current_user(); atomic_long_sub(counter->data->nr_pages + 1, &user->locked_vm); vma->vm_mm->locked_vm -= counter->data->nr_locked; perf_mmap_data_free(counter); mutex_unlock(&counter->mmap_mutex); } } static struct vm_operations_struct perf_mmap_vmops = { .open = perf_mmap_open, .close = perf_mmap_close, .fault = perf_mmap_fault, .page_mkwrite = perf_mmap_fault, }; static int perf_mmap(struct file *file, struct vm_area_struct *vma) { struct perf_counter *counter = file->private_data; unsigned long user_locked, user_lock_limit; struct user_struct *user = current_user(); unsigned long locked, lock_limit; unsigned long vma_size; unsigned long nr_pages; long user_extra, extra; int ret = 0; if (!(vma->vm_flags & VM_SHARED)) return -EINVAL; vma_size = vma->vm_end - vma->vm_start; nr_pages = (vma_size / PAGE_SIZE) - 1; /* * If we have data pages ensure they're a power-of-two number, so we * can do bitmasks instead of modulo. */ if (nr_pages != 0 && !is_power_of_2(nr_pages)) return -EINVAL; if (vma_size != PAGE_SIZE * (1 + nr_pages)) return -EINVAL; if (vma->vm_pgoff != 0) return -EINVAL; WARN_ON_ONCE(counter->ctx->parent_ctx); mutex_lock(&counter->mmap_mutex); if (atomic_inc_not_zero(&counter->mmap_count)) { if (nr_pages != counter->data->nr_pages) ret = -EINVAL; goto unlock; } user_extra = nr_pages + 1; user_lock_limit = sysctl_perf_counter_mlock >> (PAGE_SHIFT - 10); /* * Increase the limit linearly with more CPUs: */ user_lock_limit *= num_online_cpus(); user_locked = atomic_long_read(&user->locked_vm) + user_extra; extra = 0; if (user_locked > user_lock_limit) extra = user_locked - user_lock_limit; lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; lock_limit >>= PAGE_SHIFT; locked = vma->vm_mm->locked_vm + extra; if ((locked > lock_limit) && !capable(CAP_IPC_LOCK)) { ret = -EPERM; goto unlock; } WARN_ON(counter->data); ret = perf_mmap_data_alloc(counter, nr_pages); if (ret) goto unlock; atomic_set(&counter->mmap_count, 1); atomic_long_add(user_extra, &user->locked_vm); vma->vm_mm->locked_vm += extra; counter->data->nr_locked = extra; if (vma->vm_flags & VM_WRITE) counter->data->writable = 1; unlock: mutex_unlock(&counter->mmap_mutex); vma->vm_flags |= VM_RESERVED; vma->vm_ops = &perf_mmap_vmops; return ret; } static int perf_fasync(int fd, struct file *filp, int on) { struct inode *inode = filp->f_path.dentry->d_inode; struct perf_counter *counter = filp->private_data; int retval; mutex_lock(&inode->i_mutex); retval = fasync_helper(fd, filp, on, &counter->fasync); mutex_unlock(&inode->i_mutex); if (retval < 0) return retval; return 0; } static const struct file_operations perf_fops = { .release = perf_release, .read = perf_read, .poll = perf_poll, .unlocked_ioctl = perf_ioctl, .compat_ioctl = perf_ioctl, .mmap = perf_mmap, .fasync = perf_fasync, }; /* * Perf counter wakeup * * If there's data, ensure we set the poll() state and publish everything * to user-space before waking everybody up. */ void perf_counter_wakeup(struct perf_counter *counter) { wake_up_all(&counter->waitq); if (counter->pending_kill) { kill_fasync(&counter->fasync, SIGIO, counter->pending_kill); counter->pending_kill = 0; } } /* * Pending wakeups * * Handle the case where we need to wakeup up from NMI (or rq->lock) context. * * The NMI bit means we cannot possibly take locks. Therefore, maintain a * single linked list and use cmpxchg() to add entries lockless. */ static void perf_pending_counter(struct perf_pending_entry *entry) { struct perf_counter *counter = container_of(entry, struct perf_counter, pending); if (counter->pending_disable) { counter->pending_disable = 0; perf_counter_disable(counter); } if (counter->pending_wakeup) { counter->pending_wakeup = 0; perf_counter_wakeup(counter); } } #define PENDING_TAIL ((struct perf_pending_entry *)-1UL) static DEFINE_PER_CPU(struct perf_pending_entry *, perf_pending_head) = { PENDING_TAIL, }; static void perf_pending_queue(struct perf_pending_entry *entry, void (*func)(struct perf_pending_entry *)) { struct perf_pending_entry **head; if (cmpxchg(&entry->next, NULL, PENDING_TAIL) != NULL) return; entry->func = func; head = &get_cpu_var(perf_pending_head); do { entry->next = *head; } while (cmpxchg(head, entry->next, entry) != entry->next); set_perf_counter_pending(); put_cpu_var(perf_pending_head); } static int __perf_pending_run(void) { struct perf_pending_entry *list; int nr = 0; list = xchg(&__get_cpu_var(perf_pending_head), PENDING_TAIL); while (list != PENDING_TAIL) { void (*func)(struct perf_pending_entry *); struct perf_pending_entry *entry = list; list = list->next; func = entry->func; entry->next = NULL; /* * Ensure we observe the unqueue before we issue the wakeup, * so that we won't be waiting forever. * -- see perf_not_pending(). */ smp_wmb(); func(entry); nr++; } return nr; } static inline int perf_not_pending(struct perf_counter *counter) { /* * If we flush on whatever cpu we run, there is a chance we don't * need to wait. */ get_cpu(); __perf_pending_run(); put_cpu(); /* * Ensure we see the proper queue state before going to sleep * so that we do not miss the wakeup. -- see perf_pending_handle() */ smp_rmb(); return counter->pending.next == NULL; } static void perf_pending_sync(struct perf_counter *counter) { wait_event(counter->waitq, perf_not_pending(counter)); } void perf_counter_do_pending(void) { __perf_pending_run(); } /* * Callchain support -- arch specific */ __weak struct perf_callchain_entry *perf_callchain(struct pt_regs *regs) { return NULL; } /* * Output */ struct perf_output_handle { struct perf_counter *counter; struct perf_mmap_data *data; unsigned long head; unsigned long offset; int nmi; int sample; int locked; unsigned long flags; }; static bool perf_output_space(struct perf_mmap_data *data, unsigned int offset, unsigned int head) { unsigned long tail; unsigned long mask; if (!data->writable) return true; mask = (data->nr_pages << PAGE_SHIFT) - 1; /* * Userspace could choose to issue a mb() before updating the tail * pointer. So that all reads will be completed before the write is * issued. */ tail = ACCESS_ONCE(data->user_page->data_tail); smp_rmb(); offset = (offset - tail) & mask; head = (head - tail) & mask; if ((int)(head - offset) < 0) return false; return true; } static void perf_output_wakeup(struct perf_output_handle *handle) { atomic_set(&handle->data->poll, POLL_IN); if (handle->nmi) { handle->counter->pending_wakeup = 1; perf_pending_queue(&handle->counter->pending, perf_pending_counter); } else perf_counter_wakeup(handle->counter); } /* * Curious locking construct. * * We need to ensure a later event doesn't publish a head when a former * event isn't done writing. However since we need to deal with NMIs we * cannot fully serialize things. * * What we do is serialize between CPUs so we only have to deal with NMI * nesting on a single CPU. * * We only publish the head (and generate a wakeup) when the outer-most * event completes. */ static void perf_output_lock(struct perf_output_handle *handle) { struct perf_mmap_data *data = handle->data; int cpu; handle->locked = 0; local_irq_save(handle->flags); cpu = smp_processor_id(); if (in_nmi() && atomic_read(&data->lock) == cpu) return; while (atomic_cmpxchg(&data->lock, -1, cpu) != -1) cpu_relax(); handle->locked = 1; } static void perf_output_unlock(struct perf_output_handle *handle) { struct perf_mmap_data *data = handle->data; unsigned long head; int cpu; data->done_head = data->head; if (!handle->locked) goto out; again: /* * The xchg implies a full barrier that ensures all writes are done * before we publish the new head, matched by a rmb() in userspace when * reading this position. */ while ((head = atomic_long_xchg(&data->done_head, 0))) data->user_page->data_head = head; /* * NMI can happen here, which means we can miss a done_head update. */ cpu = atomic_xchg(&data->lock, -1); WARN_ON_ONCE(cpu != smp_processor_id()); /* * Therefore we have to validate we did not indeed do so. */ if (unlikely(atomic_long_read(&data->done_head))) { /* * Since we had it locked, we can lock it again. */ while (atomic_cmpxchg(&data->lock, -1, cpu) != -1) cpu_relax(); goto again; } if (atomic_xchg(&data->wakeup, 0)) perf_output_wakeup(handle); out: local_irq_restore(handle->flags); } static void perf_output_copy(struct perf_output_handle *handle, const void *buf, unsigned int len) { unsigned int pages_mask; unsigned int offset; unsigned int size; void **pages; offset = handle->offset; pages_mask = handle->data->nr_pages - 1; pages = handle->data->data_pages; do { unsigned int page_offset; int nr; nr = (offset >> PAGE_SHIFT) & pages_mask; page_offset = offset & (PAGE_SIZE - 1); size = min_t(unsigned int, PAGE_SIZE - page_offset, len); memcpy(pages[nr] + page_offset, buf, size); len -= size; buf += size; offset += size; } while (len); handle->offset = offset; /* * Check we didn't copy past our reservation window, taking the * possible unsigned int wrap into account. */ WARN_ON_ONCE(((long)(handle->head - handle->offset)) < 0); } #define perf_output_put(handle, x) \ perf_output_copy((handle), &(x), sizeof(x)) static int perf_output_begin(struct perf_output_handle *handle, struct perf_counter *counter, unsigned int size, int nmi, int sample) { struct perf_mmap_data *data; unsigned int offset, head; int have_lost; struct { struct perf_event_header header; u64 id; u64 lost; } lost_event; /* * For inherited counters we send all the output towards the parent. */ if (counter->parent) counter = counter->parent; rcu_read_lock(); data = rcu_dereference(counter->data); if (!data) goto out; handle->data = data; handle->counter = counter; handle->nmi = nmi; handle->sample = sample; if (!data->nr_pages) goto fail; have_lost = atomic_read(&data->lost); if (have_lost) size += sizeof(lost_event); perf_output_lock(handle); do { offset = head = atomic_long_read(&data->head); head += size; if (unlikely(!perf_output_space(data, offset, head))) goto fail; } while (atomic_long_cmpxchg(&data->head, offset, head) != offset); handle->offset = offset; handle->head = head; if ((offset >> PAGE_SHIFT) != (head >> PAGE_SHIFT)) atomic_set(&data->wakeup, 1); if (have_lost) { lost_event.header.type = PERF_EVENT_LOST; lost_event.header.misc = 0; lost_event.header.size = sizeof(lost_event); lost_event.id = counter->id; lost_event.lost = atomic_xchg(&data->lost, 0); perf_output_put(handle, lost_event); } return 0; fail: atomic_inc(&data->lost); perf_output_unlock(handle); out: rcu_read_unlock(); return -ENOSPC; } static void perf_output_end(struct perf_output_handle *handle) { struct perf_counter *counter = handle->counter; struct perf_mmap_data *data = handle->data; int wakeup_events = counter->attr.wakeup_events; if (handle->sample && wakeup_events) { int events = atomic_inc_return(&data->events); if (events >= wakeup_events) { atomic_sub(wakeup_events, &data->events); atomic_set(&data->wakeup, 1); } } perf_output_unlock(handle); rcu_read_unlock(); } static u32 perf_counter_pid(struct perf_counter *counter, struct task_struct *p) { /* * only top level counters have the pid namespace they were created in */ if (counter->parent) counter = counter->parent; return task_tgid_nr_ns(p, counter->ns); } static u32 perf_counter_tid(struct perf_counter *counter, struct task_struct *p) { /* * only top level counters have the pid namespace they were created in */ if (counter->parent) counter = counter->parent; return task_pid_nr_ns(p, counter->ns); } static void perf_counter_output(struct perf_counter *counter, int nmi, struct perf_sample_data *data) { int ret; u64 sample_type = counter->attr.sample_type; struct perf_output_handle handle; struct perf_event_header header; u64 ip; struct { u32 pid, tid; } tid_entry; struct { u64 id; u64 counter; } group_entry; struct perf_callchain_entry *callchain = NULL; int callchain_size = 0; u64 time; struct { u32 cpu, reserved; } cpu_entry; header.type = 0; header.size = sizeof(header); header.misc = PERF_EVENT_MISC_OVERFLOW; header.misc |= perf_misc_flags(data->regs); if (sample_type & PERF_SAMPLE_IP) { ip = perf_instruction_pointer(data->regs); header.type |= PERF_SAMPLE_IP; header.size += sizeof(ip); } if (sample_type & PERF_SAMPLE_TID) { /* namespace issues */ tid_entry.pid = perf_counter_pid(counter, current); tid_entry.tid = perf_counter_tid(counter, current); header.type |= PERF_SAMPLE_TID; header.size += sizeof(tid_entry); } if (sample_type & PERF_SAMPLE_TIME) { /* * Maybe do better on x86 and provide cpu_clock_nmi() */ time = sched_clock(); header.type |= PERF_SAMPLE_TIME; header.size += sizeof(u64); } if (sample_type & PERF_SAMPLE_ADDR) { header.type |= PERF_SAMPLE_ADDR; header.size += sizeof(u64); } if (sample_type & PERF_SAMPLE_ID) { header.type |= PERF_SAMPLE_ID; header.size += sizeof(u64); } if (sample_type & PERF_SAMPLE_CPU) { header.type |= PERF_SAMPLE_CPU; header.size += sizeof(cpu_entry); cpu_entry.cpu = raw_smp_processor_id(); } if (sample_type & PERF_SAMPLE_PERIOD) { header.type |= PERF_SAMPLE_PERIOD; header.size += sizeof(u64); } if (sample_type & PERF_SAMPLE_GROUP) { header.type |= PERF_SAMPLE_GROUP; header.size += sizeof(u64) + counter->nr_siblings * sizeof(group_entry); } if (sample_type & PERF_SAMPLE_CALLCHAIN) { callchain = perf_callchain(data->regs); if (callchain) { callchain_size = (1 + callchain->nr) * sizeof(u64); header.type |= PERF_SAMPLE_CALLCHAIN; header.size += callchain_size; } } ret = perf_output_begin(&handle, counter, header.size, nmi, 1); if (ret) return; perf_output_put(&handle, header); if (sample_type & PERF_SAMPLE_IP) perf_output_put(&handle, ip); if (sample_type & PERF_SAMPLE_TID) perf_output_put(&handle, tid_entry); if (sample_type & PERF_SAMPLE_TIME) perf_output_put(&handle, time); if (sample_type & PERF_SAMPLE_ADDR) perf_output_put(&handle, data->addr); if (sample_type & PERF_SAMPLE_ID) perf_output_put(&handle, counter->id); if (sample_type & PERF_SAMPLE_CPU) perf_output_put(&handle, cpu_entry); if (sample_type & PERF_SAMPLE_PERIOD) perf_output_put(&handle, data->period); /* * XXX PERF_SAMPLE_GROUP vs inherited counters seems difficult. */ if (sample_type & PERF_SAMPLE_GROUP) { struct perf_counter *leader, *sub; u64 nr = counter->nr_siblings; perf_output_put(&handle, nr); leader = counter->group_leader; list_for_each_entry(sub, &leader->sibling_list, list_entry) { if (sub != counter) sub->pmu->read(sub); group_entry.id = sub->id; group_entry.counter = atomic64_read(&sub->count); perf_output_put(&handle, group_entry); } } if (callchain) perf_output_copy(&handle, callchain, callchain_size); perf_output_end(&handle); } /* * read event */ struct perf_read_event { struct perf_event_header header; u32 pid; u32 tid; u64 value; u64 format[3]; }; static void perf_counter_read_event(struct perf_counter *counter, struct task_struct *task) { struct perf_output_handle handle; struct perf_read_event event = { .header = { .type = PERF_EVENT_READ, .misc = 0, .size = sizeof(event) - sizeof(event.format), }, .pid = perf_counter_pid(counter, task), .tid = perf_counter_tid(counter, task), .value = atomic64_read(&counter->count), }; int ret, i = 0; if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) { event.header.size += sizeof(u64); event.format[i++] = counter->total_time_enabled; } if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) { event.header.size += sizeof(u64); event.format[i++] = counter->total_time_running; } if (counter->attr.read_format & PERF_FORMAT_ID) { u64 id; event.header.size += sizeof(u64); if (counter->parent) id = counter->parent->id; else id = counter->id; event.format[i++] = id; } ret = perf_output_begin(&handle, counter, event.header.size, 0, 0); if (ret) return; perf_output_copy(&handle, &event, event.header.size); perf_output_end(&handle); } /* * fork tracking */ struct perf_fork_event { struct task_struct *task; struct { struct perf_event_header header; u32 pid; u32 ppid; } event; }; static void perf_counter_fork_output(struct perf_counter *counter, struct perf_fork_event *fork_event) { struct perf_output_handle handle; int size = fork_event->event.header.size; struct task_struct *task = fork_event->task; int ret = perf_output_begin(&handle, counter, size, 0, 0); if (ret) return; fork_event->event.pid = perf_counter_pid(counter, task); fork_event->event.ppid = perf_counter_pid(counter, task->real_parent); perf_output_put(&handle, fork_event->event); perf_output_end(&handle); } static int perf_counter_fork_match(struct perf_counter *counter) { if (counter->attr.comm || counter->attr.mmap) return 1; return 0; } static void perf_counter_fork_ctx(struct perf_counter_context *ctx, struct perf_fork_event *fork_event) { struct perf_counter *counter; if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list)) return; rcu_read_lock(); list_for_each_entry_rcu(counter, &ctx->event_list, event_entry) { if (perf_counter_fork_match(counter)) perf_counter_fork_output(counter, fork_event); } rcu_read_unlock(); } static void perf_counter_fork_event(struct perf_fork_event *fork_event) { struct perf_cpu_context *cpuctx; struct perf_counter_context *ctx; cpuctx = &get_cpu_var(perf_cpu_context); perf_counter_fork_ctx(&cpuctx->ctx, fork_event); put_cpu_var(perf_cpu_context); rcu_read_lock(); /* * doesn't really matter which of the child contexts the * events ends up in. */ ctx = rcu_dereference(current->perf_counter_ctxp); if (ctx) perf_counter_fork_ctx(ctx, fork_event); rcu_read_unlock(); } void perf_counter_fork(struct task_struct *task) { struct perf_fork_event fork_event; if (!atomic_read(&nr_comm_counters) && !atomic_read(&nr_mmap_counters)) return; fork_event = (struct perf_fork_event){ .task = task, .event = { .header = { .type = PERF_EVENT_FORK, .size = sizeof(fork_event.event), }, }, }; perf_counter_fork_event(&fork_event); } /* * comm tracking */ struct perf_comm_event { struct task_struct *task; char *comm; int comm_size; struct { struct perf_event_header header; u32 pid; u32 tid; } event; }; static void perf_counter_comm_output(struct perf_counter *counter, struct perf_comm_event *comm_event) { struct perf_output_handle handle; int size = comm_event->event.header.size; int ret = perf_output_begin(&handle, counter, size, 0, 0); if (ret) return; comm_event->event.pid = perf_counter_pid(counter, comm_event->task); comm_event->event.tid = perf_counter_tid(counter, comm_event->task); perf_output_put(&handle, comm_event->event); perf_output_copy(&handle, comm_event->comm, comm_event->comm_size); perf_output_end(&handle); } static int perf_counter_comm_match(struct perf_counter *counter) { if (counter->attr.comm) return 1; return 0; } static void perf_counter_comm_ctx(struct perf_counter_context *ctx, struct perf_comm_event *comm_event) { struct perf_counter *counter; if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list)) return; rcu_read_lock(); list_for_each_entry_rcu(counter, &ctx->event_list, event_entry) { if (perf_counter_comm_match(counter)) perf_counter_comm_output(counter, comm_event); } rcu_read_unlock(); } static void perf_counter_comm_event(struct perf_comm_event *comm_event) { struct perf_cpu_context *cpuctx; struct perf_counter_context *ctx; unsigned int size; char *comm = comm_event->task->comm; size = ALIGN(strlen(comm)+1, sizeof(u64)); comm_event->comm = comm; comm_event->comm_size = size; comm_event->event.header.size = sizeof(comm_event->event) + size; cpuctx = &get_cpu_var(perf_cpu_context); perf_counter_comm_ctx(&cpuctx->ctx, comm_event); put_cpu_var(perf_cpu_context); rcu_read_lock(); /* * doesn't really matter which of the child contexts the * events ends up in. */ ctx = rcu_dereference(current->perf_counter_ctxp); if (ctx) perf_counter_comm_ctx(ctx, comm_event); rcu_read_unlock(); } void perf_counter_comm(struct task_struct *task) { struct perf_comm_event comm_event; if (!atomic_read(&nr_comm_counters)) return; comm_event = (struct perf_comm_event){ .task = task, .event = { .header = { .type = PERF_EVENT_COMM, }, }, }; perf_counter_comm_event(&comm_event); } /* * mmap tracking */ struct perf_mmap_event { struct vm_area_struct *vma; const char *file_name; int file_size; struct { struct perf_event_header header; u32 pid; u32 tid; u64 start; u64 len; u64 pgoff; } event; }; static void perf_counter_mmap_output(struct perf_counter *counter, struct perf_mmap_event *mmap_event) { struct perf_output_handle handle; int size = mmap_event->event.header.size; int ret = perf_output_begin(&handle, counter, size, 0, 0); if (ret) return; mmap_event->event.pid = perf_counter_pid(counter, current); mmap_event->event.tid = perf_counter_tid(counter, current); perf_output_put(&handle, mmap_event->event); perf_output_copy(&handle, mmap_event->file_name, mmap_event->file_size); perf_output_end(&handle); } static int perf_counter_mmap_match(struct perf_counter *counter, struct perf_mmap_event *mmap_event) { if (counter->attr.mmap) return 1; return 0; } static void perf_counter_mmap_ctx(struct perf_counter_context *ctx, struct perf_mmap_event *mmap_event) { struct perf_counter *counter; if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list)) return; rcu_read_lock(); list_for_each_entry_rcu(counter, &ctx->event_list, event_entry) { if (perf_counter_mmap_match(counter, mmap_event)) perf_counter_mmap_output(counter, mmap_event); } rcu_read_unlock(); } static void perf_counter_mmap_event(struct perf_mmap_event *mmap_event) { struct perf_cpu_context *cpuctx; struct perf_counter_context *ctx; struct vm_area_struct *vma = mmap_event->vma; struct file *file = vma->vm_file; unsigned int size; char tmp[16]; char *buf = NULL; const char *name; if (file) { buf = kzalloc(PATH_MAX, GFP_KERNEL); if (!buf) { name = strncpy(tmp, "//enomem", sizeof(tmp)); goto got_name; } name = d_path(&file->f_path, buf, PATH_MAX); if (IS_ERR(name)) { name = strncpy(tmp, "//toolong", sizeof(tmp)); goto got_name; } } else { name = arch_vma_name(mmap_event->vma); if (name) goto got_name; if (!vma->vm_mm) { name = strncpy(tmp, "[vdso]", sizeof(tmp)); goto got_name; } name = strncpy(tmp, "//anon", sizeof(tmp)); goto got_name; } got_name: size = ALIGN(strlen(name)+1, sizeof(u64)); mmap_event->file_name = name; mmap_event->file_size = size; mmap_event->event.header.size = sizeof(mmap_event->event) + size; cpuctx = &get_cpu_var(perf_cpu_context); perf_counter_mmap_ctx(&cpuctx->ctx, mmap_event); put_cpu_var(perf_cpu_context); rcu_read_lock(); /* * doesn't really matter which of the child contexts the * events ends up in. */ ctx = rcu_dereference(current->perf_counter_ctxp); if (ctx) perf_counter_mmap_ctx(ctx, mmap_event); rcu_read_unlock(); kfree(buf); } void __perf_counter_mmap(struct vm_area_struct *vma) { struct perf_mmap_event mmap_event; if (!atomic_read(&nr_mmap_counters)) return; mmap_event = (struct perf_mmap_event){ .vma = vma, .event = { .header = { .type = PERF_EVENT_MMAP, }, .start = vma->vm_start, .len = vma->vm_end - vma->vm_start, .pgoff = vma->vm_pgoff, }, }; perf_counter_mmap_event(&mmap_event); } /* * Log sample_period changes so that analyzing tools can re-normalize the * event flow. */ struct freq_event { struct perf_event_header header; u64 time; u64 id; u64 period; }; static void perf_log_period(struct perf_counter *counter, u64 period) { struct perf_output_handle handle; struct freq_event event; int ret; if (counter->hw.sample_period == period) return; if (counter->attr.sample_type & PERF_SAMPLE_PERIOD) return; event = (struct freq_event) { .header = { .type = PERF_EVENT_PERIOD, .misc = 0, .size = sizeof(event), }, .time = sched_clock(), .id = counter->id, .period = period, }; ret = perf_output_begin(&handle, counter, sizeof(event), 1, 0); if (ret) return; perf_output_put(&handle, event); perf_output_end(&handle); } /* * IRQ throttle logging */ static void perf_log_throttle(struct perf_counter *counter, int enable) { struct perf_output_handle handle; int ret; struct { struct perf_event_header header; u64 time; u64 id; } throttle_event = { .header = { .type = PERF_EVENT_THROTTLE + 1, .misc = 0, .size = sizeof(throttle_event), }, .time = sched_clock(), .id = counter->id, }; ret = perf_output_begin(&handle, counter, sizeof(throttle_event), 1, 0); if (ret) return; perf_output_put(&handle, throttle_event); perf_output_end(&handle); } /* * Generic counter overflow handling, sampling. */ int perf_counter_overflow(struct perf_counter *counter, int nmi, struct perf_sample_data *data) { int events = atomic_read(&counter->event_limit); int throttle = counter->pmu->unthrottle != NULL; struct hw_perf_counter *hwc = &counter->hw; int ret = 0; if (!throttle) { hwc->interrupts++; } else { if (hwc->interrupts != MAX_INTERRUPTS) { hwc->interrupts++; if (HZ * hwc->interrupts > (u64)sysctl_perf_counter_sample_rate) { hwc->interrupts = MAX_INTERRUPTS; perf_log_throttle(counter, 0); ret = 1; } } else { /* * Keep re-disabling counters even though on the previous * pass we disabled it - just in case we raced with a * sched-in and the counter got enabled again: */ ret = 1; } } if (counter->attr.freq) { u64 now = sched_clock(); s64 delta = now - hwc->freq_stamp; hwc->freq_stamp = now; if (delta > 0 && delta < TICK_NSEC) perf_adjust_period(counter, NSEC_PER_SEC / (int)delta); } /* * XXX event_limit might not quite work as expected on inherited * counters */ counter->pending_kill = POLL_IN; if (events && atomic_dec_and_test(&counter->event_limit)) { ret = 1; counter->pending_kill = POLL_HUP; if (nmi) { counter->pending_disable = 1; perf_pending_queue(&counter->pending, perf_pending_counter); } else perf_counter_disable(counter); } perf_counter_output(counter, nmi, data); return ret; } /* * Generic software counter infrastructure */ static void perf_swcounter_update(struct perf_counter *counter) { struct hw_perf_counter *hwc = &counter->hw; u64 prev, now; s64 delta; again: prev = atomic64_read(&hwc->prev_count); now = atomic64_read(&hwc->count); if (atomic64_cmpxchg(&hwc->prev_count, prev, now) != prev) goto again; delta = now - prev; atomic64_add(delta, &counter->count); atomic64_sub(delta, &hwc->period_left); } static void perf_swcounter_set_period(struct perf_counter *counter) { struct hw_perf_counter *hwc = &counter->hw; s64 left = atomic64_read(&hwc->period_left); s64 period = hwc->sample_period; if (unlikely(left <= -period)) { left = period; atomic64_set(&hwc->period_left, left); hwc->last_period = period; } if (unlikely(left <= 0)) { left += period; atomic64_add(period, &hwc->period_left); hwc->last_period = period; } atomic64_set(&hwc->prev_count, -left); atomic64_set(&hwc->count, -left); } static enum hrtimer_restart perf_swcounter_hrtimer(struct hrtimer *hrtimer) { enum hrtimer_restart ret = HRTIMER_RESTART; struct perf_sample_data data; struct perf_counter *counter; u64 period; counter = container_of(hrtimer, struct perf_counter, hw.hrtimer); counter->pmu->read(counter); data.addr = 0; data.regs = get_irq_regs(); /* * In case we exclude kernel IPs or are somehow not in interrupt * context, provide the next best thing, the user IP. */ if ((counter->attr.exclude_kernel || !data.regs) && !counter->attr.exclude_user) data.regs = task_pt_regs(current); if (data.regs) { if (perf_counter_overflow(counter, 0, &data)) ret = HRTIMER_NORESTART; } period = max_t(u64, 10000, counter->hw.sample_period); hrtimer_forward_now(hrtimer, ns_to_ktime(period)); return ret; } static void perf_swcounter_overflow(struct perf_counter *counter, int nmi, struct perf_sample_data *data) { data->period = counter->hw.last_period; perf_swcounter_update(counter); perf_swcounter_set_period(counter); if (perf_counter_overflow(counter, nmi, data)) /* soft-disable the counter */ ; } static int perf_swcounter_is_counting(struct perf_counter *counter) { struct perf_counter_context *ctx; unsigned long flags; int count; if (counter->state == PERF_COUNTER_STATE_ACTIVE) return 1; if (counter->state != PERF_COUNTER_STATE_INACTIVE) return 0; /* * If the counter is inactive, it could be just because * its task is scheduled out, or because it's in a group * which could not go on the PMU. We want to count in * the first case but not the second. If the context is * currently active then an inactive software counter must * be the second case. If it's not currently active then * we need to know whether the counter was active when the * context was last active, which we can determine by * comparing counter->tstamp_stopped with ctx->time. * * We are within an RCU read-side critical section, * which protects the existence of *ctx. */ ctx = counter->ctx; spin_lock_irqsave(&ctx->lock, flags); count = 1; /* Re-check state now we have the lock */ if (counter->state < PERF_COUNTER_STATE_INACTIVE || counter->ctx->is_active || counter->tstamp_stopped < ctx->time) count = 0; spin_unlock_irqrestore(&ctx->lock, flags); return count; } static int perf_swcounter_match(struct perf_counter *counter, enum perf_type_id type, u32 event, struct pt_regs *regs) { if (!perf_swcounter_is_counting(counter)) return 0; if (counter->attr.type != type) return 0; if (counter->attr.config != event) return 0; if (regs) { if (counter->attr.exclude_user && user_mode(regs)) return 0; if (counter->attr.exclude_kernel && !user_mode(regs)) return 0; } return 1; } static void perf_swcounter_add(struct perf_counter *counter, u64 nr, int nmi, struct perf_sample_data *data) { int neg = atomic64_add_negative(nr, &counter->hw.count); if (counter->hw.sample_period && !neg && data->regs) perf_swcounter_overflow(counter, nmi, data); } static void perf_swcounter_ctx_event(struct perf_counter_context *ctx, enum perf_type_id type, u32 event, u64 nr, int nmi, struct perf_sample_data *data) { struct perf_counter *counter; if (system_state != SYSTEM_RUNNING || list_empty(&ctx->event_list)) return; rcu_read_lock(); list_for_each_entry_rcu(counter, &ctx->event_list, event_entry) { if (perf_swcounter_match(counter, type, event, data->regs)) perf_swcounter_add(counter, nr, nmi, data); } rcu_read_unlock(); } static int *perf_swcounter_recursion_context(struct perf_cpu_context *cpuctx) { if (in_nmi()) return &cpuctx->recursion[3]; if (in_irq()) return &cpuctx->recursion[2]; if (in_softirq()) return &cpuctx->recursion[1]; return &cpuctx->recursion[0]; } static void do_perf_swcounter_event(enum perf_type_id type, u32 event, u64 nr, int nmi, struct perf_sample_data *data) { struct perf_cpu_context *cpuctx = &get_cpu_var(perf_cpu_context); int *recursion = perf_swcounter_recursion_context(cpuctx); struct perf_counter_context *ctx; if (*recursion) goto out; (*recursion)++; barrier(); perf_swcounter_ctx_event(&cpuctx->ctx, type, event, nr, nmi, data); rcu_read_lock(); /* * doesn't really matter which of the child contexts the * events ends up in. */ ctx = rcu_dereference(current->perf_counter_ctxp); if (ctx) perf_swcounter_ctx_event(ctx, type, event, nr, nmi, data); rcu_read_unlock(); barrier(); (*recursion)--; out: put_cpu_var(perf_cpu_context); } void __perf_swcounter_event(u32 event, u64 nr, int nmi, struct pt_regs *regs, u64 addr) { struct perf_sample_data data = { .regs = regs, .addr = addr, }; do_perf_swcounter_event(PERF_TYPE_SOFTWARE, event, nr, nmi, &data); } static void perf_swcounter_read(struct perf_counter *counter) { perf_swcounter_update(counter); } static int perf_swcounter_enable(struct perf_counter *counter) { perf_swcounter_set_period(counter); return 0; } static void perf_swcounter_disable(struct perf_counter *counter) { perf_swcounter_update(counter); } static const struct pmu perf_ops_generic = { .enable = perf_swcounter_enable, .disable = perf_swcounter_disable, .read = perf_swcounter_read, }; /* * Software counter: cpu wall time clock */ static void cpu_clock_perf_counter_update(struct perf_counter *counter) { int cpu = raw_smp_processor_id(); s64 prev; u64 now; now = cpu_clock(cpu); prev = atomic64_read(&counter->hw.prev_count); atomic64_set(&counter->hw.prev_count, now); atomic64_add(now - prev, &counter->count); } static int cpu_clock_perf_counter_enable(struct perf_counter *counter) { struct hw_perf_counter *hwc = &counter->hw; int cpu = raw_smp_processor_id(); atomic64_set(&hwc->prev_count, cpu_clock(cpu)); hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); hwc->hrtimer.function = perf_swcounter_hrtimer; if (hwc->sample_period) { u64 period = max_t(u64, 10000, hwc->sample_period); __hrtimer_start_range_ns(&hwc->hrtimer, ns_to_ktime(period), 0, HRTIMER_MODE_REL, 0); } return 0; } static void cpu_clock_perf_counter_disable(struct perf_counter *counter) { if (counter->hw.sample_period) hrtimer_cancel(&counter->hw.hrtimer); cpu_clock_perf_counter_update(counter); } static void cpu_clock_perf_counter_read(struct perf_counter *counter) { cpu_clock_perf_counter_update(counter); } static const struct pmu perf_ops_cpu_clock = { .enable = cpu_clock_perf_counter_enable, .disable = cpu_clock_perf_counter_disable, .read = cpu_clock_perf_counter_read, }; /* * Software counter: task time clock */ static void task_clock_perf_counter_update(struct perf_counter *counter, u64 now) { u64 prev; s64 delta; prev = atomic64_xchg(&counter->hw.prev_count, now); delta = now - prev; atomic64_add(delta, &counter->count); } static int task_clock_perf_counter_enable(struct perf_counter *counter) { struct hw_perf_counter *hwc = &counter->hw; u64 now; now = counter->ctx->time; atomic64_set(&hwc->prev_count, now); hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); hwc->hrtimer.function = perf_swcounter_hrtimer; if (hwc->sample_period) { u64 period = max_t(u64, 10000, hwc->sample_period); __hrtimer_start_range_ns(&hwc->hrtimer, ns_to_ktime(period), 0, HRTIMER_MODE_REL, 0); } return 0; } static void task_clock_perf_counter_disable(struct perf_counter *counter) { if (counter->hw.sample_period) hrtimer_cancel(&counter->hw.hrtimer); task_clock_perf_counter_update(counter, counter->ctx->time); } static void task_clock_perf_counter_read(struct perf_counter *counter) { u64 time; if (!in_nmi()) { update_context_time(counter->ctx); time = counter->ctx->time; } else { u64 now = perf_clock(); u64 delta = now - counter->ctx->timestamp; time = counter->ctx->time + delta; } task_clock_perf_counter_update(counter, time); } static const struct pmu perf_ops_task_clock = { .enable = task_clock_perf_counter_enable, .disable = task_clock_perf_counter_disable, .read = task_clock_perf_counter_read, }; #ifdef CONFIG_EVENT_PROFILE void perf_tpcounter_event(int event_id) { struct perf_sample_data data = { .regs = get_irq_regs(); .addr = 0, }; if (!data.regs) data.regs = task_pt_regs(current); do_perf_swcounter_event(PERF_TYPE_TRACEPOINT, event_id, 1, 1, &data); } EXPORT_SYMBOL_GPL(perf_tpcounter_event); extern int ftrace_profile_enable(int); extern void ftrace_profile_disable(int); static void tp_perf_counter_destroy(struct perf_counter *counter) { ftrace_profile_disable(perf_event_id(&counter->attr)); } static const struct pmu *tp_perf_counter_init(struct perf_counter *counter) { int event_id = perf_event_id(&counter->attr); int ret; ret = ftrace_profile_enable(event_id); if (ret) return NULL; counter->destroy = tp_perf_counter_destroy; return &perf_ops_generic; } #else static const struct pmu *tp_perf_counter_init(struct perf_counter *counter) { return NULL; } #endif atomic_t perf_swcounter_enabled[PERF_COUNT_SW_MAX]; static void sw_perf_counter_destroy(struct perf_counter *counter) { u64 event = counter->attr.config; WARN_ON(counter->parent); atomic_dec(&perf_swcounter_enabled[event]); } static const struct pmu *sw_perf_counter_init(struct perf_counter *counter) { const struct pmu *pmu = NULL; u64 event = counter->attr.config; /* * Software counters (currently) can't in general distinguish * between user, kernel and hypervisor events. * However, context switches and cpu migrations are considered * to be kernel events, and page faults are never hypervisor * events. */ switch (event) { case PERF_COUNT_SW_CPU_CLOCK: pmu = &perf_ops_cpu_clock; break; case PERF_COUNT_SW_TASK_CLOCK: /* * If the user instantiates this as a per-cpu counter, * use the cpu_clock counter instead. */ if (counter->ctx->task) pmu = &perf_ops_task_clock; else pmu = &perf_ops_cpu_clock; break; case PERF_COUNT_SW_PAGE_FAULTS: case PERF_COUNT_SW_PAGE_FAULTS_MIN: case PERF_COUNT_SW_PAGE_FAULTS_MAJ: case PERF_COUNT_SW_CONTEXT_SWITCHES: case PERF_COUNT_SW_CPU_MIGRATIONS: if (!counter->parent) { atomic_inc(&perf_swcounter_enabled[event]); counter->destroy = sw_perf_counter_destroy; } pmu = &perf_ops_generic; break; } return pmu; } /* * Allocate and initialize a counter structure */ static struct perf_counter * perf_counter_alloc(struct perf_counter_attr *attr, int cpu, struct perf_counter_context *ctx, struct perf_counter *group_leader, struct perf_counter *parent_counter, gfp_t gfpflags) { const struct pmu *pmu; struct perf_counter *counter; struct hw_perf_counter *hwc; long err; counter = kzalloc(sizeof(*counter), gfpflags); if (!counter) return ERR_PTR(-ENOMEM); /* * Single counters are their own group leaders, with an * empty sibling list: */ if (!group_leader) group_leader = counter; mutex_init(&counter->child_mutex); INIT_LIST_HEAD(&counter->child_list); INIT_LIST_HEAD(&counter->list_entry); INIT_LIST_HEAD(&counter->event_entry); INIT_LIST_HEAD(&counter->sibling_list); init_waitqueue_head(&counter->waitq); mutex_init(&counter->mmap_mutex); counter->cpu = cpu; counter->attr = *attr; counter->group_leader = group_leader; counter->pmu = NULL; counter->ctx = ctx; counter->oncpu = -1; counter->parent = parent_counter; counter->ns = get_pid_ns(current->nsproxy->pid_ns); counter->id = atomic64_inc_return(&perf_counter_id); counter->state = PERF_COUNTER_STATE_INACTIVE; if (attr->disabled) counter->state = PERF_COUNTER_STATE_OFF; pmu = NULL; hwc = &counter->hw; hwc->sample_period = attr->sample_period; if (attr->freq && attr->sample_freq) hwc->sample_period = 1; atomic64_set(&hwc->period_left, hwc->sample_period); /* * we currently do not support PERF_SAMPLE_GROUP on inherited counters */ if (attr->inherit && (attr->sample_type & PERF_SAMPLE_GROUP)) goto done; switch (attr->type) { case PERF_TYPE_RAW: case PERF_TYPE_HARDWARE: case PERF_TYPE_HW_CACHE: pmu = hw_perf_counter_init(counter); break; case PERF_TYPE_SOFTWARE: pmu = sw_perf_counter_init(counter); break; case PERF_TYPE_TRACEPOINT: pmu = tp_perf_counter_init(counter); break; default: break; } done: err = 0; if (!pmu) err = -EINVAL; else if (IS_ERR(pmu)) err = PTR_ERR(pmu); if (err) { if (counter->ns) put_pid_ns(counter->ns); kfree(counter); return ERR_PTR(err); } counter->pmu = pmu; if (!counter->parent) { atomic_inc(&nr_counters); if (counter->attr.mmap) atomic_inc(&nr_mmap_counters); if (counter->attr.comm) atomic_inc(&nr_comm_counters); } return counter; } static int perf_copy_attr(struct perf_counter_attr __user *uattr, struct perf_counter_attr *attr) { int ret; u32 size; if (!access_ok(VERIFY_WRITE, uattr, PERF_ATTR_SIZE_VER0)) return -EFAULT; /* * zero the full structure, so that a short copy will be nice. */ memset(attr, 0, sizeof(*attr)); ret = get_user(size, &uattr->size); if (ret) return ret; if (size > PAGE_SIZE) /* silly large */ goto err_size; if (!size) /* abi compat */ size = PERF_ATTR_SIZE_VER0; if (size < PERF_ATTR_SIZE_VER0) goto err_size; /* * If we're handed a bigger struct than we know of, * ensure all the unknown bits are 0. */ if (size > sizeof(*attr)) { unsigned long val; unsigned long __user *addr; unsigned long __user *end; addr = PTR_ALIGN((void __user *)uattr + sizeof(*attr), sizeof(unsigned long)); end = PTR_ALIGN((void __user *)uattr + size, sizeof(unsigned long)); for (; addr < end; addr += sizeof(unsigned long)) { ret = get_user(val, addr); if (ret) return ret; if (val) goto err_size; } } ret = copy_from_user(attr, uattr, size); if (ret) return -EFAULT; /* * If the type exists, the corresponding creation will verify * the attr->config. */ if (attr->type >= PERF_TYPE_MAX) return -EINVAL; if (attr->__reserved_1 || attr->__reserved_2 || attr->__reserved_3) return -EINVAL; if (attr->sample_type & ~(PERF_SAMPLE_MAX-1)) return -EINVAL; if (attr->read_format & ~(PERF_FORMAT_MAX-1)) return -EINVAL; out: return ret; err_size: put_user(sizeof(*attr), &uattr->size); ret = -E2BIG; goto out; } /** * sys_perf_counter_open - open a performance counter, associate it to a task/cpu * * @attr_uptr: event type attributes for monitoring/sampling * @pid: target pid * @cpu: target cpu * @group_fd: group leader counter fd */ SYSCALL_DEFINE5(perf_counter_open, struct perf_counter_attr __user *, attr_uptr, pid_t, pid, int, cpu, int, group_fd, unsigned long, flags) { struct perf_counter *counter, *group_leader; struct perf_counter_attr attr; struct perf_counter_context *ctx; struct file *counter_file = NULL; struct file *group_file = NULL; int fput_needed = 0; int fput_needed2 = 0; int ret; /* for future expandability... */ if (flags) return -EINVAL; ret = perf_copy_attr(attr_uptr, &attr); if (ret) return ret; if (!attr.exclude_kernel) { if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN)) return -EACCES; } if (attr.freq) { if (attr.sample_freq > sysctl_perf_counter_sample_rate) return -EINVAL; } /* * Get the target context (task or percpu): */ ctx = find_get_context(pid, cpu); if (IS_ERR(ctx)) return PTR_ERR(ctx); /* * Look up the group leader (we will attach this counter to it): */ group_leader = NULL; if (group_fd != -1) { ret = -EINVAL; group_file = fget_light(group_fd, &fput_needed); if (!group_file) goto err_put_context; if (group_file->f_op != &perf_fops) goto err_put_context; group_leader = group_file->private_data; /* * Do not allow a recursive hierarchy (this new sibling * becoming part of another group-sibling): */ if (group_leader->group_leader != group_leader) goto err_put_context; /* * Do not allow to attach to a group in a different * task or CPU context: */ if (group_leader->ctx != ctx) goto err_put_context; /* * Only a group leader can be exclusive or pinned */ if (attr.exclusive || attr.pinned) goto err_put_context; } counter = perf_counter_alloc(&attr, cpu, ctx, group_leader, NULL, GFP_KERNEL); ret = PTR_ERR(counter); if (IS_ERR(counter)) goto err_put_context; ret = anon_inode_getfd("[perf_counter]", &perf_fops, counter, 0); if (ret < 0) goto err_free_put_context; counter_file = fget_light(ret, &fput_needed2); if (!counter_file) goto err_free_put_context; counter->filp = counter_file; WARN_ON_ONCE(ctx->parent_ctx); mutex_lock(&ctx->mutex); perf_install_in_context(ctx, counter, cpu); ++ctx->generation; mutex_unlock(&ctx->mutex); counter->owner = current; get_task_struct(current); mutex_lock(¤t->perf_counter_mutex); list_add_tail(&counter->owner_entry, ¤t->perf_counter_list); mutex_unlock(¤t->perf_counter_mutex); fput_light(counter_file, fput_needed2); out_fput: fput_light(group_file, fput_needed); return ret; err_free_put_context: kfree(counter); err_put_context: put_ctx(ctx); goto out_fput; } /* * inherit a counter from parent task to child task: */ static struct perf_counter * inherit_counter(struct perf_counter *parent_counter, struct task_struct *parent, struct perf_counter_context *parent_ctx, struct task_struct *child, struct perf_counter *group_leader, struct perf_counter_context *child_ctx) { struct perf_counter *child_counter; /* * Instead of creating recursive hierarchies of counters, * we link inherited counters back to the original parent, * which has a filp for sure, which we use as the reference * count: */ if (parent_counter->parent) parent_counter = parent_counter->parent; child_counter = perf_counter_alloc(&parent_counter->attr, parent_counter->cpu, child_ctx, group_leader, parent_counter, GFP_KERNEL); if (IS_ERR(child_counter)) return child_counter; get_ctx(child_ctx); /* * Make the child state follow the state of the parent counter, * not its attr.disabled bit. We hold the parent's mutex, * so we won't race with perf_counter_{en, dis}able_family. */ if (parent_counter->state >= PERF_COUNTER_STATE_INACTIVE) child_counter->state = PERF_COUNTER_STATE_INACTIVE; else child_counter->state = PERF_COUNTER_STATE_OFF; if (parent_counter->attr.freq) child_counter->hw.sample_period = parent_counter->hw.sample_period; /* * Link it up in the child's context: */ add_counter_to_ctx(child_counter, child_ctx); /* * Get a reference to the parent filp - we will fput it * when the child counter exits. This is safe to do because * we are in the parent and we know that the filp still * exists and has a nonzero count: */ atomic_long_inc(&parent_counter->filp->f_count); /* * Link this into the parent counter's child list */ WARN_ON_ONCE(parent_counter->ctx->parent_ctx); mutex_lock(&parent_counter->child_mutex); list_add_tail(&child_counter->child_list, &parent_counter->child_list); mutex_unlock(&parent_counter->child_mutex); return child_counter; } static int inherit_group(struct perf_counter *parent_counter, struct task_struct *parent, struct perf_counter_context *parent_ctx, struct task_struct *child, struct perf_counter_context *child_ctx) { struct perf_counter *leader; struct perf_counter *sub; struct perf_counter *child_ctr; leader = inherit_counter(parent_counter, parent, parent_ctx, child, NULL, child_ctx); if (IS_ERR(leader)) return PTR_ERR(leader); list_for_each_entry(sub, &parent_counter->sibling_list, list_entry) { child_ctr = inherit_counter(sub, parent, parent_ctx, child, leader, child_ctx); if (IS_ERR(child_ctr)) return PTR_ERR(child_ctr); } return 0; } static void sync_child_counter(struct perf_counter *child_counter, struct task_struct *child) { struct perf_counter *parent_counter = child_counter->parent; u64 child_val; perf_counter_read_event(child_counter, child); child_val = atomic64_read(&child_counter->count); /* * Add back the child's count to the parent's count: */ atomic64_add(child_val, &parent_counter->count); atomic64_add(child_counter->total_time_enabled, &parent_counter->child_total_time_enabled); atomic64_add(child_counter->total_time_running, &parent_counter->child_total_time_running); /* * Remove this counter from the parent's list */ WARN_ON_ONCE(parent_counter->ctx->parent_ctx); mutex_lock(&parent_counter->child_mutex); list_del_init(&child_counter->child_list); mutex_unlock(&parent_counter->child_mutex); /* * Release the parent counter, if this was the last * reference to it. */ fput(parent_counter->filp); } static void __perf_counter_exit_task(struct perf_counter *child_counter, struct perf_counter_context *child_ctx, struct task_struct *child) { struct perf_counter *parent_counter; update_counter_times(child_counter); perf_counter_remove_from_context(child_counter); parent_counter = child_counter->parent; /* * It can happen that parent exits first, and has counters * that are still around due to the child reference. These * counters need to be zapped - but otherwise linger. */ if (parent_counter) { sync_child_counter(child_counter, child); free_counter(child_counter); } } /* * When a child task exits, feed back counter values to parent counters. */ void perf_counter_exit_task(struct task_struct *child) { struct perf_counter *child_counter, *tmp; struct perf_counter_context *child_ctx; unsigned long flags; if (likely(!child->perf_counter_ctxp)) return; local_irq_save(flags); /* * We can't reschedule here because interrupts are disabled, * and either child is current or it is a task that can't be * scheduled, so we are now safe from rescheduling changing * our context. */ child_ctx = child->perf_counter_ctxp; __perf_counter_task_sched_out(child_ctx); /* * Take the context lock here so that if find_get_context is * reading child->perf_counter_ctxp, we wait until it has * incremented the context's refcount before we do put_ctx below. */ spin_lock(&child_ctx->lock); child->perf_counter_ctxp = NULL; if (child_ctx->parent_ctx) { /* * This context is a clone; unclone it so it can't get * swapped to another process while we're removing all * the counters from it. */ put_ctx(child_ctx->parent_ctx); child_ctx->parent_ctx = NULL; } spin_unlock(&child_ctx->lock); local_irq_restore(flags); /* * We can recurse on the same lock type through: * * __perf_counter_exit_task() * sync_child_counter() * fput(parent_counter->filp) * perf_release() * mutex_lock(&ctx->mutex) * * But since its the parent context it won't be the same instance. */ mutex_lock_nested(&child_ctx->mutex, SINGLE_DEPTH_NESTING); again: list_for_each_entry_safe(child_counter, tmp, &child_ctx->counter_list, list_entry) __perf_counter_exit_task(child_counter, child_ctx, child); /* * If the last counter was a group counter, it will have appended all * its siblings to the list, but we obtained 'tmp' before that which * will still point to the list head terminating the iteration. */ if (!list_empty(&child_ctx->counter_list)) goto again; mutex_unlock(&child_ctx->mutex); put_ctx(child_ctx); } /* * free an unexposed, unused context as created by inheritance by * init_task below, used by fork() in case of fail. */ void perf_counter_free_task(struct task_struct *task) { struct perf_counter_context *ctx = task->perf_counter_ctxp; struct perf_counter *counter, *tmp; if (!ctx) return; mutex_lock(&ctx->mutex); again: list_for_each_entry_safe(counter, tmp, &ctx->counter_list, list_entry) { struct perf_counter *parent = counter->parent; if (WARN_ON_ONCE(!parent)) continue; mutex_lock(&parent->child_mutex); list_del_init(&counter->child_list); mutex_unlock(&parent->child_mutex); fput(parent->filp); list_del_counter(counter, ctx); free_counter(counter); } if (!list_empty(&ctx->counter_list)) goto again; mutex_unlock(&ctx->mutex); put_ctx(ctx); } /* * Initialize the perf_counter context in task_struct */ int perf_counter_init_task(struct task_struct *child) { struct perf_counter_context *child_ctx, *parent_ctx; struct perf_counter_context *cloned_ctx; struct perf_counter *counter; struct task_struct *parent = current; int inherited_all = 1; int ret = 0; child->perf_counter_ctxp = NULL; mutex_init(&child->perf_counter_mutex); INIT_LIST_HEAD(&child->perf_counter_list); if (likely(!parent->perf_counter_ctxp)) return 0; /* * This is executed from the parent task context, so inherit * counters that have been marked for cloning. * First allocate and initialize a context for the child. */ child_ctx = kmalloc(sizeof(struct perf_counter_context), GFP_KERNEL); if (!child_ctx) return -ENOMEM; __perf_counter_init_context(child_ctx, child); child->perf_counter_ctxp = child_ctx; get_task_struct(child); /* * If the parent's context is a clone, pin it so it won't get * swapped under us. */ parent_ctx = perf_pin_task_context(parent); /* * No need to check if parent_ctx != NULL here; since we saw * it non-NULL earlier, the only reason for it to become NULL * is if we exit, and since we're currently in the middle of * a fork we can't be exiting at the same time. */ /* * Lock the parent list. No need to lock the child - not PID * hashed yet and not running, so nobody can access it. */ mutex_lock(&parent_ctx->mutex); /* * We dont have to disable NMIs - we are only looking at * the list, not manipulating it: */ list_for_each_entry_rcu(counter, &parent_ctx->event_list, event_entry) { if (counter != counter->group_leader) continue; if (!counter->attr.inherit) { inherited_all = 0; continue; } ret = inherit_group(counter, parent, parent_ctx, child, child_ctx); if (ret) { inherited_all = 0; break; } } if (inherited_all) { /* * Mark the child context as a clone of the parent * context, or of whatever the parent is a clone of. * Note that if the parent is a clone, it could get * uncloned at any point, but that doesn't matter * because the list of counters and the generation * count can't have changed since we took the mutex. */ cloned_ctx = rcu_dereference(parent_ctx->parent_ctx); if (cloned_ctx) { child_ctx->parent_ctx = cloned_ctx; child_ctx->parent_gen = parent_ctx->parent_gen; } else { child_ctx->parent_ctx = parent_ctx; child_ctx->parent_gen = parent_ctx->generation; } get_ctx(child_ctx->parent_ctx); } mutex_unlock(&parent_ctx->mutex); perf_unpin_context(parent_ctx); return ret; } static void __cpuinit perf_counter_init_cpu(int cpu) { struct perf_cpu_context *cpuctx; cpuctx = &per_cpu(perf_cpu_context, cpu); __perf_counter_init_context(&cpuctx->ctx, NULL); spin_lock(&perf_resource_lock); cpuctx->max_pertask = perf_max_counters - perf_reserved_percpu; spin_unlock(&perf_resource_lock); hw_perf_counter_setup(cpu); } #ifdef CONFIG_HOTPLUG_CPU static void __perf_counter_exit_cpu(void *info) { struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context); struct perf_counter_context *ctx = &cpuctx->ctx; struct perf_counter *counter, *tmp; list_for_each_entry_safe(counter, tmp, &ctx->counter_list, list_entry) __perf_counter_remove_from_context(counter); } static void perf_counter_exit_cpu(int cpu) { struct perf_cpu_context *cpuctx = &per_cpu(perf_cpu_context, cpu); struct perf_counter_context *ctx = &cpuctx->ctx; mutex_lock(&ctx->mutex); smp_call_function_single(cpu, __perf_counter_exit_cpu, NULL, 1); mutex_unlock(&ctx->mutex); } #else static inline void perf_counter_exit_cpu(int cpu) { } #endif static int __cpuinit perf_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { unsigned int cpu = (long)hcpu; switch (action) { case CPU_UP_PREPARE: case CPU_UP_PREPARE_FROZEN: perf_counter_init_cpu(cpu); break; case CPU_DOWN_PREPARE: case CPU_DOWN_PREPARE_FROZEN: perf_counter_exit_cpu(cpu); break; default: break; } return NOTIFY_OK; } /* * This has to have a higher priority than migration_notifier in sched.c. */ static struct notifier_block __cpuinitdata perf_cpu_nb = { .notifier_call = perf_cpu_notify, .priority = 20, }; void __init perf_counter_init(void) { perf_cpu_notify(&perf_cpu_nb, (unsigned long)CPU_UP_PREPARE, (void *)(long)smp_processor_id()); register_cpu_notifier(&perf_cpu_nb); } static ssize_t perf_show_reserve_percpu(struct sysdev_class *class, char *buf) { return sprintf(buf, "%d\n", perf_reserved_percpu); } static ssize_t perf_set_reserve_percpu(struct sysdev_class *class, const char *buf, size_t count) { struct perf_cpu_context *cpuctx; unsigned long val; int err, cpu, mpt; err = strict_strtoul(buf, 10, &val); if (err) return err; if (val > perf_max_counters) return -EINVAL; spin_lock(&perf_resource_lock); perf_reserved_percpu = val; for_each_online_cpu(cpu) { cpuctx = &per_cpu(perf_cpu_context, cpu); spin_lock_irq(&cpuctx->ctx.lock); mpt = min(perf_max_counters - cpuctx->ctx.nr_counters, perf_max_counters - perf_reserved_percpu); cpuctx->max_pertask = mpt; spin_unlock_irq(&cpuctx->ctx.lock); } spin_unlock(&perf_resource_lock); return count; } static ssize_t perf_show_overcommit(struct sysdev_class *class, char *buf) { return sprintf(buf, "%d\n", perf_overcommit); } static ssize_t perf_set_overcommit(struct sysdev_class *class, const char *buf, size_t count) { unsigned long val; int err; err = strict_strtoul(buf, 10, &val); if (err) return err; if (val > 1) return -EINVAL; spin_lock(&perf_resource_lock); perf_overcommit = val; spin_unlock(&perf_resource_lock); return count; } static SYSDEV_CLASS_ATTR( reserve_percpu, 0644, perf_show_reserve_percpu, perf_set_reserve_percpu ); static SYSDEV_CLASS_ATTR( overcommit, 0644, perf_show_overcommit, perf_set_overcommit ); static struct attribute *perfclass_attrs[] = { &attr_reserve_percpu.attr, &attr_overcommit.attr, NULL }; static struct attribute_group perfclass_attr_group = { .attrs = perfclass_attrs, .name = "perf_counters", }; static int __init perf_counter_sysfs_init(void) { return sysfs_create_group(&cpu_sysdev_class.kset.kobj, &perfclass_attr_group); } device_initcall(perf_counter_sysfs_init);